3. A 57-year-old lady on the transplant waiting list for 11 years. Her primary disease is analgesic nephropathy. A family friend came forward for donation. The mismatch is 121, FCXM is positive for both B and T cells. Auto-crossmatch is also negative. There was no DSA detected.
- How do you explain this cross match?
- If you decided not to go ahead, what is your alternative?
- If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
- What is the role of desensitization in this case?
Dear All
There are 15 free places to be offered the the highest scores to join the programme “Practical Approach to Transplant Immunology”. The deadline for submission is tomorrow at midnight. Write your answer below.
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies
D. The crossmatch assay is performed to prevent hyperacute rejection
E. Responds to steroid pulse
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway
B. C4d deposition is known to cause severe graft injury in renal transplantation
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies
D. C4d is highly stable and persists at the cell surface for a long time periods
E. C4d with tubulitis indicates mixed rejection
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye.
D. Antibodies in the serum are usually of the IgM subclass.
E. Both are replaced by FCXM, Luminex-SAB and cPRA.
1- A,E
2- D,E
3- B,E
1- A,E
2-D,E
3-B,E
1. A/E
2. E
3. B/E
1/A..F acute antibody mediated rejection can occur anytime post transplant
B…T
C…T
D….T
E….F ABMR resistant to steroids and needs IVIG ,PE and rutiximab
So wrong answers are A,E
2/ A..T
B…F
C…T
D…T
E…F
SO answers are b,E
3/A…F
B…T
C….F
D….F
E…..T
so answer is B.E
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. False ABMR can occur many years post transplantations due to the formation of de novo DSA or it can occur early if there is pre-formed DSA.
B. True these are the sources of sensitization and represent risk factors for ABMR.
C. True pre-formed DSA of high level is a risk factor for hyperacute rejection.
D. True the aim of pretransplant crossmatching is to prevent hyperacute rejection mediated by anti HLA antibodies directed against the donor.
E. False the usual treatment for ABMR is PE+ IVIG.
2.Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. True C4d is derived from C4b which is related to the classical pathway.
B. False both C4d positive and C4d negative ABMR are associated with severe graft damage and poor graft outcome, and studies suggest that the association of C4d with other morphological aspects has more prognostic value like TMA.
C. True the presence of circulating anti-donor antibodies will lead to ABMR in which their is peritubular C4d deposition.
D. True C4d is covalently bound to the tissue, has much longer half life, and remains at the site of complement activation.
E. True C4d is a sign of ABMR and tubulitis is a sign of cellular rejection.
3.Which statement(s) regarding CDC and PRA is/are correct?
A. False HLA antigens are present on the nucleated cells, RBCs lack the nucleus.
B. True the binding of the antibodies to the antigens leads to complement system activation and the formation of membrane attack complex which leads to cell lysis.
C. False the formation of membrane attack complex will leads to cell death and lysis.
D. False antibodies in the serum are usually of IgG type. Autoantibodies are of IgM type.
E. True to increase the sensitivity and specificity of these tests, a new methods replaced them, so CDC is replaced by FCXM, and PRA is now replaced by cPRA using Luminex-SAB testing.
1-A,E
2-E
3-B,E
1-A, E
as AMR can occur any time post-transplantion and classified into Early AMR and Late AMR according to time of onset. AMR does not respond to treatment with steroid alone and it requires treatment with IVIg, PE a t rituximab
2- B, E
C4d depotions isn’t not always associated with destructive response as in case of late AMR and in chronic AMR C4d deposits may reflect accomodative response rather than destructive process. Also may occur due to endothelial exposure to sublytic level of the complement and as C4d is an inactive particle that’s not needed for formation of membrane attack complex so may present without concomitant graft damage
3-B, E
1. Which of the following statement(s) about antibody-mediated rejection is/are NOT correct?
A, E not correct
False A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation ,
ABMR can occur at any time, opposite to hyperacute
True B. Risk factors for antibody-mediated rejection include multiple transplantations, previous pregnancies, and a history of blood transfusions
True C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies
True D. The crossmatch assay is performed to prevent hyperacute rejection
FLASE E. Responds to steroid pulse
T cell-mediated rejection is managed with pulse steroids as first-line followed by depleting agents. On the other hand, ABMR eeds removal of antibodies and neutralizng so we need plasmapheresis/immunadsorptin with IVIG as well as rituximab or eculizumab
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
B not correct
True A. C4d is a fragment of C4 produced during the classic complement activation pathway
FALSE B. C4d deposition is known to cause severe graft injury in renal transplantation
C4d deposition may be present without rejection as well it maybe not be stained in cases of ABMR
True C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies
True D. C4d is highly stable and persists at the cell surface for a long time periods
True E. C4d with tubulitis indicates mixed rejection (tubulits is a feature of TCMR), we may have ABMR without c4d staining
3. Which statement(s) regarding CDC and PRA is/are correct?
B correct
FLASE A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.
RBC do not express MHC antigens
TRUE B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
FLASE: C. Formation of the membrane attack complex causes the donor macrophages to take up the dye. We have two dies, one for vital while the other for non-vital. After cell membrane lysis the stain of non-vital cells
FLASE D. Antibodies in the serum are usually of the IgM subclass.
Antibodies are usually IgG class
False E. Both are replaced by FCXM, Luminex-SAB and cPRA.
Still CDC is cornerstone, FCMX, luminex have their handicaps. Furthermore, SAB may be falsely positive because of denaured epitope used in the assay (misleading)
1- A, E
2- B
3- B, E
1/ A and E
2/ B
3/A ,C and D
١_Aand E.
2_DandE
.
3_BandE.
1-Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
answer
A,D,E,
A-False, AMR can occur early and late , at any time after the transplantion
B-True
C-True
D-False the crossmatch is one of the immunological assay that help in identify the immunological risk of the recipient and help in allocation of comaptbale donor
E-false,, TCMR ususlaly responding to steriod while AMR treatment target to remove the DSAs AB like plasmaphersis , IVIG plus rituximab
.
2-Which of the following statement(s) regarding C4d deposition is/are NOT correct?
the answer B is false
both C4d positive complement mediated AMR and C4D negative AMR associated with sever microvascular inflammation in ABMR and associated with poor graft survival
A-True
B-False
C-True
D-True
E-True
3-Which statement(s) regarding CDC and PRA is/are correct?
the correct answer B
A- False detection of antibodies in the all nucleated cells accept RBCs
B-true
C-False complement activation led to cell lysis
D-False antibodies are IgG and non HLA but IgM are referred to autoABs
E-False , still CDC crossmatch one of the cornerstone first test to be done espcially in low risk , LD programm the others yes they are the prefered more sensitive and sepecific espicialy in high immunological risk patients and previous;y sensitized patients and DD program .
Q1: A & E
AMR can occur at both early and late time after TX.
Q2: B & E
C4d disposition is used as a marker of AMR and is not necessary related to graft damage.
C4d is a marker of AMR and tubulitis indicates TCMR. So presence of both of them indicates mixed rejection.
Q3: B
A is false because HLA-Ag are not expressed on Red Blood cells.
B is correct.
C is false because formation of MAC causes donor lymphocytes lysis and uptake of the dye.
D is false because anti-HLA antibodies are usually of IgG subclasses and IgM antibodies are usually auto-antibodies.
E is false because although FCXM and Luminax are more sensitive but performing CDC-XM is considered contraindications for TX.
CPRA is indicative of unacceptable antigens.
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation
Acute ABMR has Early and Late AMR, two different clinical entities. Early AMR which occurs in the first few days few days to weeks after transplantation. Late acute AMR also can be diagnosed months to years after kidney transplantation
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies
D. The crossmatch assay is performed to prevent hyperacute rejection
E. Responds to steroid pulse- a rapid rise in DSA with an allograft biopsy showing few chronic changes might be reversible and thus might benefit from eculizumab therapy if PE is unsuccessful.
So, answers are A and E
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway
B. C4d deposition is known to cause severe graft injury in renal transplantation -C4d deposition in the PTC is a marker of antibody -mediated rejection, but there is no evidence that it is causally related to graft injury.
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies
D. C4d is highly stable and persists at the cell surface for a long time periods
E. C4d with tubulitis indicates mixed rejection
so, Answer is B
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.- RBCs are lack of nucleated cells, HLA antigens are present on the nucleated cell
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye.- it causes cells to lyse and death
D. Antibodies in the serum are usually of the IgM subclass. – Antibodies in the serum are usually of IgG . Only autoantibodies are of IgM type.
E. Both are replaced by FCXM, Luminex-SAB and cPRA.
So, Answer are B and E
1- A &E
2- B
3-B &E
1.A,E
2.B ,E
3.B ,E
1-A and E
2-B
3-B and E
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation F
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions T
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies T
D. The crossmatch assay is performed to prevent hyperacute rejection F
E. Responds to steroid pulse F
A, D and E are not correct.
Acute ABMR can occur early and late after kidney transplantation, in a multicenter cohort study, antibody-mediated damage caused allograft dysfunction late posttransplant in nearly 60% of renal transplant recipients.
Allosensitization to HLA proteins occurs after pregnancy, blood transfusion or transplantation.
Hyperacute rejection occurs immediately upon reperfusion and is attributed to preformed donor-specific antibodies to HLA.
Crossmatched assay is not only performed to prevent hyperacute rejection, another important purpose of crossmatch assays is as a risk assessment tool for antibody-mediated rejection, which is one of the main barriers to improve long-term graft outcomes.
For treatment of ABMR steroid in combination with plasmapheresis, IVIG, and other drugs such as Rituximab are used.
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway T
B. C4d deposition is known to cause severe graft injury in renal transplantation F
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies T
D. C4d is highly stable and persists at the cell surface for a long time periods F
E. C4d with tubulitis indicates mixed rejection T
B and D are not correct.
C4d is a split product of C4 involved in the classical complement cascade. C4d is a marker for recent complement activation.
C4d staining is not clearly associated with any short or long-term deleterious effect on graft outcome.
C4d staining in peritubular capillaries was recognized to be associated with the presence of DSA and the equivalence of C4d and DSA on graft outcome was proven.
C4d is a marker for recent complement activation.
C4d with tubulitis may indicate mixed rejection.
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells. F
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex. T
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye. F
D. Antibodies in the serum are usually of the IgM subclass. F
E. Both are replaced by FCXM, Luminex-SAB and cPRA. T
B and E are correct.
Both assays test for presence of antibodies directed against antigens expressed on lymphocytes.
Formation of the membrane attack complex causes the donor lymphocyte cell lysis.
Antibodies in the serum are usually of the IgG subclass.
Although the CDC-XM is still widely used by many transplant centres, over the years it has mostly been superseded by new crossmatch techniques with higher sensitivity and specificity.
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
Answer: A, E
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation. False: can occur early (due to pre-existing antibodies) or late (due to de-novo antibodies usually)
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions True
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies True
D. The crossmatch assay is performed to prevent hyperacute rejection True
E. Responds to steroid pulse False: Is steroid non-responsive, needs Plasmapheresis, IVIG and other treatment
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
Answer: B, E
A. C4d is a fragment of C4 produced during the classic complement activation pathway True: But it can also be formed through lectin pathway
B. C4d deposition is known to cause severe graft injury in renal transplantation False: C4d deposition per se does not cause graft injury. C4d positivity can be seen in accommodation in ABO incompatible transplants. C4d negative AMR is also seen
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies True: C4d deposition in PTC is specific for presence of circulating anti-donor antibodies
D. C4d is highly stable and persists at the cell surface for a long time periods True
E. C4d with tubulitis indicates mixed rejection False: Tubulitis is a feature of T cell mediated rejection but C4d deposition in peritubular capillaries (and not at other sites) is a specific marker for AMR
3. Which statement(s) regarding CDC and PRA is/are correct?
Answer: B
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells. False: They test antibodies against nucleated cells (RBC do not have nuclei)
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex. True
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye. False: MAC formation leads to cell lysis
D. Antibodies in the serum are usually of the IgM subclass. False: Usually they are IgG
E. Both are replaced by FCXM, Luminex-SAB and cPRA. False: CDC is still being used. These newer tests have increased sensitivity.
1- A , E
2- B
3- B , E
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation-FALSE
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions –TRUE
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies –TRUE
D. The crossmatch assay is performed to prevent hyperacute rejection –TRUE
E. Responds to steroid pulse- FALSE
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway- TRUE
B. C4d deposition is known to cause severe graft injury in renal transplantation- FALSE
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies – TRUE
D. C4d is highly stable and persists at the cell surface for a long time periods- TRUE
E. C4d with tubulitis indicates mixed rejection- TRUE
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells- FALSE
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.- TRUE
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye- FALSE
D. Antibodies in the serum are usually of the IgM subclass- FALSE
E. Both are replaced by FCXM, Luminex-SAB and cPRA- TRUE
1- A , E
2-B , E
3-B , E
ANSWERS
Referrences:
1.C4d Deposition without Rejection Correlates with Reduced Early Scarring in ABO-Incompatible Renal Allografts
Mark Haas, Dorry L. Segev, Lorraine C. Racusen, Serena M. Bagnasco, Jayme E. Locke, Daniel S. Warren, Christopher E. Simpkins, Diane Lepley, Karen E. King, Edward S. Kraus and Robert A. Montgomery JASN January 2009, 20 (1) 197-204; DOI: https://doi.org/10.1681/ASN.2008030279
2.Neutrophilic tubulitis as a marker for urinary tract infection in renal allograft biopsies with C4d deposition
Gaurav Gupta 1 , Ron Shapiro, Alin Girnita, Ibrahim Batal, Jerry McCauley, Amit Basu, Henkie Tan, Parmjeet Randhawa(https://pubmed.ncbi.nlm.nih.gov/19352120/#:~:text=actions-,Cite,-Favorites)
3.A positive complement dependent cytotoxicity immunoglobulin G crossmatch due to auto-antibodies with a negative luminex bead assays in a renal transplant recipient: A Diagnostic dilemma
Mohit Chowdhry, Raj Nath Makroo, Brinda Kakkar,1 Yogita Thakur, Manoj Kumar, and Mandhata Singh
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation. True (ABMR can occur early and can occur late)
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions. False (not Not correct—>>>correct information)
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies. False (not Not correct—->correct information)
D. The crossmatch assay is performed to prevent hyperacute rejection. False (not Not correct——>correct information)
E. Responds to steroid pulse. True (usually needs Plasma exchange and IVIG)
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway. False (not Not correct—–>correct information)
B. C4d deposition is known to cause severe graft injury in renal transplantation. True (C4d is not associated with any short or long-term deleterious effect on graftoutcome.
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies False (not Not correct——>correct information)
D. C4d is highly stable and persists at the cell surface for a long time periods. False (not Not correct—–>correct information) Covalently bound C4d has a higher chance to remain at the site of complement activation than the antibodies themselves, which dissociate over time. C4d is anchored tightly to the tissue and therefore acts as a footprint of antibody-mediated tissue injury.
E. C4d with tubulitis indicates mixed rejection. False (not Not correct—–>correct
information
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.False(against antigens on all nucleated cells, RBCs are not nucleated)
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.True
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye. False( leads to cell lysis)
D. Antibodies in the serum are usually of the IgM subclass.False(usually IgG)
E. Both are replaced by FCXM, Luminex-SAB and cPRA. True
1- A. not correct, acute AMR may occur at any time post transplant
E. not correct, treatment of AMR include plasmapheresis and IVIG
2- B. not correct, C4d is biologically inactive, bound to peritubular capillaries and used as marker of recent complement activation
C. not correct, Although it is a marker of AMR, but is of low sensitivity and molecular studies determined C4d negative AMR, also C4d deposition may occur with or without circulating DSA in incompatible ABO transplantation
3- B. correct
E. correct
1 . A,E
2 . B
3 . B,E
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation .False
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions .True
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies .True
D. The crossmatch assay is performed to prevent hyperacute rejection.True
E. Responds to steroid pulse.False
AMR may be of the following types: hyperacute, acute, and chronic. Hyperacute AMR occurs due to preformed donor-specific antibodies present in high titers, and it presents as graft failure that can occur within minutes or a few days after transplantation.
Acute AMR is characterized by graft dysfunction manifesting over days, and it is a result of donor-specific antibodies, which may either be preexisting or develop de novo after transplantation.
Chronic AMR, which is characteristically seen as transplant glomeru- lopathy in kidney biopsies, is characterized by glomerular mesangial expansion and capillary basement membrane duplication or splitting, interstitial fibrosis/tubular atrophy, and/or fibrous intimal thickening in arteries. Sometimes, peritubular capillary basement membrane multilayering is also observed on electron microscopy
Current strategies for the treatment of AMR include antibody depletion with plasmapheresis (PLEX), immunoadsorption (IA), immunomodulation with intravenous immunoglobulin (IVIG), and T cell– or B cell–depleting agents.
Reference
Rosana Rosa Miranda Corrêa,. The Importance of C4d in Biopsies of Kidney Transplant Recipients
Hindawi Publishing Corporation
Clinical and Developmental Immunology Volume 2013, Article ID 678180, 8 pages http://dx.doi.org/10.1155/2013/678180
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway.True
B. C4d deposition is known to cause severe graft injury in renal transplantation .False
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies .True
D. C4d is highly stable and persists at the cell surface for a long time periods .True
E. C4d with tubulitis indicates mixed rejection.True
C4d-negative antibody-mediated rejection,” which appears to be at least as common as C4d-positive AMR and has similar poor prognosis in terms of graft survival
The major functions of the complement system are to promote phagocytosis by opsonization of microorganisms and/or the host’s own cells under certain conditions; to stimulate inflammation through the interaction of mediators of the complement system and receptors in phagocytic cells; and to cause direct cell lysis by forming the MAC
Diagnosis of AMR requires the simultaneous presence of donor-specific antibodies, distinctive histopathological find- ings, and C4d deposition in peritubular capillaries (PTCs)
Tubulitis indicates T cell mediated rejection
References
Rosana Rosa Miranda Corrêa,. The Importance of C4d in Biopsies of Kidney Transplant Recipients
Hindawi Publishing Corporation
Clinical and Developmental Immunology Volume 2013, Article ID 678180, 8 pages http://dx.doi.org/10.1155/2013/678180
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.False
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.True
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye.False
D. Antibodies in the serum are usually of the IgM subclass.False
E. Both are replaced by FCXM, Luminex-SAB and cPRA. True
The human leukocyte antigen (HLA) system (the major histocompatibility complex [MHC] in humans) is an important part of the immune system and is controlled by genes located on chromosome 6.
Class I MHC molecules are present as transmembrane glycoproteins on the surface of all nucleated cells.
Class II MHC molecules are usually present only on professional antigen-presenting cells (B cells, macrophages, dendritic cells, Langerhans cells), thymic epithelium, and activated (but not resting) T cells; most nucleated cells can be induced to express class II MHC molecules by interferon (IFN)-gamma.
The major functions of the complement system are to promote phagocytosis by opsonization of microorganisms and/or the host’s own cells under certain conditions; to stimulate inflammation through the interaction of mediators of the complement system and receptors in phagocytic cells; and to cause direct cell lysis by forming the MAC
DSA are IgG antibodies
FCXM and Luminex are more sensitive than CDC and PRA
Reference
Peter J. Delves
PhD, University College London, London, UK
Human Leukocyte Antigen (HLA) System
Last full review/revision Sep 2021| Content last modified Sep 2021
1: A , E
2: B
3:B , E
1
=======
A. False
As ABMR can occur at any time due to formation of de no novo antibodies
B. True
C. True
D. True
E. False
ABMR is treated with PE+ IVIG.
So the answers are A,E
2
=======
A. True
B. False
Not only c4d associated with severe graft injury also c4d negative may be associated with severe graft injury .
C. True
D. True
E. True
C4d is a sign of ABMR while tubulitis is a sign of cellular rejection.
So the answer B
3
=====
A. False
As RBC not nucleated and not antigen presenting cell while HLA class 1 present in all nucleated cells and class II present in antigen presenting cells
B. True
C. False
the formation of membrane attack complex will leads to cell lysis .
D. False
antibodies in the serum are usually of IgG type.
E. True
So the answers are B, E
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies
D
E. Responds to steroid pulse
(A):false (B):correct (C):correct (D):correct (E):False
Acute antibody-mediated rejection can occur both at early times post transplantation ( erlay acute antibody-mediated rejection) , and late after 6 months post transplantation ( Late acute antibody-mediated rejection).
Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions as it cause sensitization of the patient through production of varients of alloantibodies. high levels of pre-existing anti-donor antibodies can cause Hyperacute rejection. .
positive crossmatch assay denotes the presence of preformed DSA, thus it is crucial to be performed done to prevent hyperacute rejection.
AMR shows poor response to steroids however main lines of treatment include plasma exchange, IV IG, anti plasma cell(bortezomi), anti CD20 (Ruximab), anti IL6 (Tsilizmab), anti complement (EUclizumab)
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway
B. C4d deposition is known to cause severe graft injury in renal transplantation
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies
D. C4d is highly stable and persists at the cell surface for a long time periods
E. C4d with tubulitis indicates mixed rejection
(A):true, (B):false, (C): true, (D):false (E):false
C4d is a fragment of C4 produced during the classic complement activation pathway , C4d deposition in peritubular capillaries (PTCs) by itself is not injurious to the graft tissue, otherwise it is of diagnostic and prognostic value denoting mostly AMR . Hence it correlates with the presence of circulating anti-donor antibodies
C4d is a dynamic marker since it can accumulate and disappear within days (4–8 days). Occasionally, C4d is detected persistently over many months
Although C4D positive staining can be used as a marker for ABMR. , it may be positive without rejection in ABO incompatible grafts. However, C4d deposition without AMR has been observed even in transplant glomerulopathy (TG), Accordingly C4D with tubulitis ( which is a histologic fature of CMR) is not necesserly coincides with mixed AMR /CMR
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye.
D. Antibodies in the serum are usually of the IgM subclass.
E. Both are replaced by FCXM, Luminex-SAB and cPRA.
(A): false , (B)True (C)true (D):false (E)true
Both assays, CDC and PRA test for the presence of antibodies directed against HLA antigens expressed on neucleated cells , classified into class I and II. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
In positive CDC test , the presence of anti HLA AB will bind HLA on cell suface in the presence of complement will end in Formation of the membrane attack complex causes the donor macrophages to lyse and take up the dye.
Antibodies in the serum are usually of the IgM and IgG subclass, both techniques are now replaced by FCXM, Luminex-SAB and cPRA for high sensitivity and less false positive and negative results
Dear Dr Ahmed,
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
The answer is A, E.
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
The answer is B, C, D.
3. Which statement(s) regarding CDC and PRA is/are correct?
The answer is B, E.
Q1:
A: False.
Acute antibody mediated rejection occur at any time post transplant.
B.True.
C.True.
D.True.
E.False. It is resistant to steroid need IVIG + plasma exchange with rituximab .
Incorrect answers (A,E)
Q2:
A.True.
B.False, C4d positive and negative ABMR cause sever graft injury and poor outcome .
C.True.
D.True.
E.False,tubulitis occurs with T cell mediated rejection but c4d in peritubular capillaries.
Incorrect answers (B,E)
Q3:
A.False,HLA antigen presented in all nucleated cells , RBCS lack in nucleus.
B.True.
C.False, formation of MAC lead to cells lysis and death will occur to cells.
D.False.Antibodies in serum usually IgG, autoantibodies IgM.
E.False, CDC still used .
Incorrect answers (A,C,D,E)
1- A, E
A, E are not correct. AMR can occur at any time, and yes a negative crossmatch assay coupled with proper ABO matching will effectively prevent hyperacute rejection in 99.5% of transplants. AMR might need Rituximab, PE and IVIGs.
2- B, E.
B is not correct. C4d is a complement fragment, generated through classic pathway activation and is covalently bound to antigen. Peritubular capillary deposition of C4d in the PTC is a marker of antibody – mediated rejection & has been demonstrated to be associated with both acute humoral and vascular rejection. No evidence that C4d is related to graft injury. C4d and tubulitis can occur in case of AMR.
3- B, E
B, E, are correct. CDC crossmatch was performed using neat, and dithiothreitol (DTT) treated patients’ sera and lymphocytes (B and T-cells were separated) of the donor or patient (for autocrossmatch). Binding of C1q triggers the activation of the complement cascade and leads to the formation of the membrane attack complex (MAC). The fluorescent dye is used to assess cell lysis; hence the dead lymphocytes will take up the dye. Antibodies in the serum are usually of IgG type
1. Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies
D
E. Responds to steroid pulse
(A): false (B): correct (C): correct (D): correct (E): False
Acute antibody-mediated rejection can occur both at early times post transplantation ( erlay acute antibody-mediated rejection) , and late after 6 months post transplantation ( Late acute antibody-mediated rejection).
Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions as it cause sensitization of the patient through production of varients of alloantibodies. high levels of pre-existing anti-donor antibodies can cause Hyperacute rejection. .
positive crossmatch assay denotes the presence of preformed DSA, thus it is crucial to be performed done to prevent hyperacute rejection.
AMR shows poor response to steroids however main lines of treatment include plasma exchange, IV IG, anti plasma cell(bortezomi), anti CD20 (Ruximab), anti IL6 (Tsilizmab), anti complement (EUclizumab)
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway
B. C4d deposition is known to cause severe graft injury in renal transplantation
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies
D. C4d is highly stable and persists at the cell surface for a long time periods
E. C4d with tubulitis indicates mixed rejection
(A):true, (B):false, (C):true, (D):false (E):false
C4d is a fragment of C4 produced during the classic complement activation pathway , C4d deposition in peritubular capillaries (PTCs) by itself is not injurious to the graft tissue, otherwise it is of diagnostic and prognostic value denoting mostly AMR . Hence it correlates with the presence of circulating anti-donor antibodies
C4d is a dynamic marker since it can accumulate and disappear within days (4–8 days). Occasionally, C4d is detected persistently over many months
Although C4D positive staining can be used as a marker for ABMR. , it may be positive without rejection in ABO incompatible grafts. However, C4d deposition without AMR has been observed even in transplant glomerulopathy (TG), Accordingly C4D with tubulitis ( which is a histologic fature of CMR) is not necesserly coincides with mixed AMR /CMR
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells.
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye.
D. Antibodies in the serum are usually of the IgM subclass.
E. Both are replaced by FCXM, Luminex-SAB and cPRA.
(A): false , (B)True (C)true (D):false (E) false
Both assays, CDC and PRA test for the presence of antibodies directed against HLA antigens expressed on neucleated cells , classified into class I and II. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex.
In positive CDC test , the presence of anti HLA AB will bind HLA on cell suface in the presence of complement will end in Formation of the membrane attack complex causes the donor macrophages to lyse and take up the dye.
Antibodies in the serum are usually of the IgM and IgG subclass, both techniques, , Luminex-SAB and cPRA are not replaced by FCXM , they altogether used for patient assessment and risk stratification. cPRA for initial assessment of the presence of preformed DSA and hence patients chance for having a compitable donor . FCXM highly sensitive for detection of anti DSA (preformed), Luminex-SAB foe HLA typing needed for evaluation for donor HLA mismatching to detect the severity of allogenic immuneresponse ond formation of Denovo DSA
Answre to MCQ
1 A and E
2 B
3 B and E
1-A: Acute antibody-mediated rejection can occurs at any time post transplantation
E: ABMR not responding to pulse steroids alone ,it needs other measures to remove preformed antibodies and inhibition of formation of new antibodies.
2-C :50 % of ABMR are C4d negative.
3-A : Mature human red blood cells are not nucleated and do not generally have detectable HLA antigens.
D: Antibodies in the serum are usually of the IgG subclass.
1 :A and E
2: B,C,D
3. B
1 A
2 b
3 A E
Dear prof ; The answer A being correct in question 3 is confusing me as both tests CDC and PRA are done on T& B lymphocytes and NOT red blood cells. May you can clarify it for us.
Sir,
Apologies for the very late reply….
1- How do you explain this cross match?
2- If you decided not to go ahead, what is your alternative?
3- If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
4- What is the role of desensitization in this case?
None HL a antibodies may explain positive Crossmatch
if I decided not to go ahead I may wait for another donor if I decided to go ahead and transplant this lady I will give induction with ATG and the maintenance immunosuppression TAC MMF steroids
role of desensitization in this case will be due to positive crossmatch to achieve negative crossmatch with plasmapheresis and IV IG
A positive B and T cell FCXM in the absence of Donor specific antibody indicates either low level DSA which is not picked up luminex assay, non HLA antibodies. It also depend on the timeline of the DSA and FCXM,. If FCXM is recently done and DSA is done before, ideally a repeat DSA needs to be done. FCXM are done easily as compared to DSA due to cost constraints. Use of Rituximab may lead Positive B cell FCXM as seen in many ABO incompatible renal transplants. But here, although DSA is negative, Both T cell and B cell FCXM are positive indicating antibodies against Class I and Class II antigens. Autocross match is negative indicating no auto antibodies against the Class I and Class II.
As this transplant is a high risk case, due to the presence of HLA 121 mismatch and positive FCXM, it needs desensitization with Plasmaphresis and IVIG one week before transplant. I would give 3 sessions of Plasmaphresis 1.5 times the volume replacement and IVIG 5GM IV every day for 5 days…I would repeat the FCXM cross match and make sure the T cell FCXM is negative before transplantation. The B cell FCXM maybe positive if rituximab was used, but there is no such history in this case. I would proceed for transplant only if the FCXM becomes negative.
Either desensitization or paired donor exchange
How do you explain this cross match?
Positive FXCM with negative DSA
Causes
1-Non HLA antibodies
2-Prior therapeutic use of monoclonal antibodies (rituximab ) but usually it affects B cell only and here FXCM positive in both B and T cells
3- False positive
If you decided not to go ahead, what is your alternative?
Donor paired exchange
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
ATG in induction , Tac-MMF-steroid in maintainable )
What is the role of desensitization in this case?
If we going to proceed desensitization should be done with Plasmapheresis, IVIG and rituximab
FCMXM + B +T : is either due to DSA or non HLA , IGM, AutoAB
-ve Auto XM excludes the presence of AutoAB
No detected DSA could be explained by either the presence of IGM in high concentrations ( hook effect or prozone effect) or the presence of high levels of DSAs leadin to Ig agglutination resultin in false negative SPI
So a positive FCM XM with no DSA could either be explained by the presence of non HLA AB, or DSA with the hook effect of IgM, or the agglutination
Alternaives include further waiting on a list or paired kidney exchange programme
(1)Induction ATG
(2)Desensitization protocol ( Rituximab, IV IG, )
(3)Tripple immune suppression protocol ( steroids, MMF, Tac)
To convert patient from FCMXM + to – ( highly expected to develop AMR
To eliminate the development of Denovo DSAs due to the HLA mismatch
• How do you explain this cross match?
Positive T and B cell FCXM may be due to presence of non HLA antibodies or low DSA titer
auto crossmatch is negative
• If you decided not to go ahead, what is your alternative?
Either waiting for more comparable doner or shifting to Paired exchange donation
• If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
1- Desensitization
2- ATG induction
3- Maintenance (steroid,MMF,TAG)
• What is the role of desensitization in this case?
In this case we need to do desensitization because we have positive FCXM
To decrease the risk of antibody mediated rejection
Up to date 2021
How do you explain this cross match?
FCXM can be positive with non HLA antibodies , luminex SAB detects only HLA AB
So this postive FCXM might be to non HLA ab
Or may be false negative Luminex-SAB due to denatured antigen
you decided not to go ahead, what is your alternative?
I prefer to find another doner with better match as transplantation against positive FCXM carry a high risk of rejection even with non HLA antibodies
I will offer the patient paired kidney exchange
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
First i will do desensitization until FCXM be negative.
Induction with ATG
Mentinance on triple immunosuppression
tacrolimus,MMF and steroids.
What is the role of desensitization in this case?
transplanting against positive FXCM both tcell and b cell carry high risk of graft rejection its better to do desensitization with plasma exchange and IVIG
And repeat FCXM TILL its negative with follow up Of DSA 1and 3 months posttransplantation .
Cross match positive with undetectable DSA may be due to antibodies against non-HLA antigens in this case .
Wait for another donor or kidney paired donation if available
immunosuppression protocol?
High risk due to the HLA mismatches and positive FCMx
Desensitization to achieve a negative cross match
Induction with ATG then maintenance IS with triple therapy Tacrolimus, MMf and steroids
close monitoring of DSA 3 ,6 ,12
What is the role of desensitization in this case
Although response to desensitization therapy of non-HLA antibodies have not been clearly established , it should be initiated aiming to achieve -ve Cross match
How do you explain this cross match?
Flowcytometry crossmatch is wet cross match using recipient b and t cell against ab in donor serum
It can be positive due to both HLA antibodies or non HLA antibodies and also positive for complement fixing and non complement fixing antibodies
On the other hand solid phase crossmatch by single antigen bead by luminex is the most sensitive test in detection antibodies against only HLA antigens
The explanation for positive TCXM and negative DSA is non HLA antibodies or lab error due to SAP antigen denaturation
If you decided not to go ahead, what is your alternative?
Offer this patient the option to do paired kidney donation if available to get better matching and better FCXM
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
desensitization is still controverse in such case but i will do CDC CM and repeat FCXM after 2w i will go for desensitization until FCXT become negative as few studies showed increase risk of rejection with non HLA antibodies then rATG or campath induction followed by triple immunosuppressant medications tac,MMF and steroids
What is the role of desensitization in this case?
Still controverse but it more convenient because you are transplanting against positive FXCM both tcell and b cell
Answre to MCQ
1 A and E
2 B
3 B and E
+ve FCXM with negative DSA mean the patient had non HLA antibodies which need confirmed by SAB, & offer paired kidney exchange to get more suitable donor. If recipient decide to precede with his current donor she should be desensitized with PP + IVIG & rituximab, induction with T cell depleting agent & maintenance IS ( CNI, MMF & low dose steroids) with close follow-up of DSA.
Desensitization to get negative cross-match.
Kang H., Yoo J., and Lee S. et al. Causes of Positive Pretransplant Crossmatches in the Absence of Donor-Specific Anti-Human Leukocyte Antigen Antibodies: A Single-Center Experience. Ann Lab Med, 2021; 41: 429-435.
Positive FXCM with negative CDC and DSA negative could be related to non complement fixing Ab, non HLA Ab and low level of Ab also in patients who are treated with anti CD 20 Ab this patient has high risk of graft loss but it isn’t contraindication of transplantation, for this pt. With this mismatch better to find another donor or kidney paired donation if this difficult desensitization with plx and IVIG prior to transplantation then put the patient on triple IS (steroids,MMF and tacrolimus) with DSA monitoring .
The role of desensitization is to reach to negative crossmatch and to decrease post transplant risk of rejection.
In this 1 HLA-A/-DR 2/6 mismatch as both T and B flow crossmach are positive one could expect DSA to be positive by anti HLA-A and antibodies to -DR (!!!)
non-HLA antibodies such those againts endothelial cells may cause flow cytometry to be positive as the are circulşating but may not be detected by assasy using lymphocytes (as there non-HLa antibodies are not present on lyphocytes) so DSA is negative
this is a high risk patient and should be desenseized and dealed with as high rish patient. we need depleting agents here most widely available is rATG; could be preferred to other agents. I may use 3 days of rATG 1.5 mg/kg with standard 500 mg prednidolone tapered according to standard regimen . this patient is eligible for TAC/MMF/Steroid maintainance
The HLA typing is 4/6 mismatch, positive FCXM for both B & T cells, negative autocrossmatch & there was no DSA , so FCXM is inconsistent with DSA & negative autocrossmatch ( no autoantibodies ) the causes might be the followings:
1- Recent anti CD20 treatment, from her history the cause of ESRD was analgesic nephropathy, she might have recent anti CD20 treatment for rheumatic arthritis as rituximab, which affected the FCXM, so, we need pronase treatment of donor lymphocytes.
2- Incomplete donor typing, consult with HLA laprotoroy experts (DSA present ).
3-The Prozone effect, need 1:8 serum dilution if cPRA>80%
4Alloantibody to shared epitopes, consider testing for non-HLA alloantibody ., all indicating that high-risk transplant. The alternatives for this transplant are paired exchange or search for another donor.
If we decided to go ahead with this donor, it is an immunological high-risk transplant, it needs desensitization, Rituximab, plasmapheresis &IVIG, induction with ATG, & maintenance immunosuppressive medications( tacrolimus, MMF & steroid ).
The role of desensitization is FXCM to become negative ( washout antibodies).
References
Interperting Anti HLA antibody Testing data ( transplanation 2016,00:00-00).
1- Which of the following statement(s) about antibody- mediated rejection is/are NOT correct?
A. Acute antibody-mediated rejection occurs only at early time points after organ transplantation
B. Risk factors for antibody-mediated rejection include multiple transplantation, previous pregnancies, and a history of blood transfusions
C. Hyperacute rejection is mediated by high levels of pre-existing anti-donor antibodies
D. The crossmatch assay is performed to prevent hyperacute rejection
E. Responds to steroid pulse
A, E are wrong
2. Which of the following statement(s) regarding C4d deposition is/are NOT correct?
A. C4d is a fragment of C4 produced during the classic complement activation pathway (T). Its fragment of of C4b
B. C4d deposition is known to cause severe graft injury in renal transplantation (F)
C. C4d deposition in the peritubular capillaries correlates with the presence of circulating anti-donor antibodies (F)
D. C4d is highly stable and persists at the cell surface for a long time periods (T)
E. C4d with tubulitis indicates mixed rejection (T)
B,C, not correct
3. Which statement(s) regarding CDC and PRA is/are correct?
A. Both assays test for the presence of antibodies directed against antigens expressed on Red Blood Cells. F
B. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex. T
C. Formation of the membrane attack complex causes the donor macrophages to take up the dye. F
D. Antibodies in the serum are usually of the IgM subclass. F
E. Both are replaced by FCXM, Luminex-SAB and cPRA. F
Answer B
To provide negative FCXM
1-due to low sensitivity of CDC than flowcytometry
2-patient mostly highly sensitized so recommend use of plasma exchange and retuximab then go for transplant with other compatible one (exchange protocol)
3-ATG induction as it high risk
then (tac,mmf,cortisol) as maintenance
4-it have a big role for making patient more suitable for transplantation & decrease risk of early rejection
How do you explain this cross match?
Most probably it is Non HLA antibodies
If you decided not to go ahead, what is your alternative?
1.Searching for another donor
2.Paired exchange
3.Continue waiting in deceased donations list
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
Induction with ATG,Tac ,MMF and predinsilone as maintenance
What is the role of desensitization in this case?
No role because I had no measurable antibodies
1-A&E
2-B&E
3-B&E
Q1:
Her positive FCXM is due to non-HLA antibodies.
Q2: Change the donor or a paired kidney donation with negative FCXM and lower HLA mismatches
Q3: We need a potent immunosuppression with ATG or alemtuzumab and triple maintenance immunosuppression by tacrolimus, MMF and prednisolone.
Q4: Performing transplantation with a positive FCXM especially T cell is associated with poor graft outcome and although unclear but desensitization with plasmapheresis, IVIG and rituximab to achieve a negative XM is helpful.
cross match positive with undetectable DSA may be due to low titre of anti-HLA antibodies, antibodies reacting with self epitopes shared by donor cells or antibodies against non-HLA antigens
waiting for another donor or kidney paired donation if available
high immunological risk due to the HLA mismatches and positive crossmatch
desensitization till have negative cross match
induction with thymoglobulin tthen maintenance immunosuppression with triple therapy Tacrolimus, MMf and steroids
post transplant close monitoring of DSA
desensitization to render the crossmatch negative
although response to desensitization therapy of non-HLA antibodies have not been clearly established.
Downing J. The lymphocyte crossmatch by flow cytometry for kidney transplantation. InImmunogenetics 2012 (pp. 379-390). Humana Press, Totowa, NJ.
Zhang Q, Reed EF. The importance of non-HLA antibodies in transplantation. Nature Reviews Nephrology. 2016 Aug;12(8):484-95.
This is a patient with 121 HLA mismatches, B and T cell FCXM+ and negative for DSAs. HLA mismatches are associated with poor patient and graft survival, and even in the absence of performed DSA, increases the probability of de novo DSA formation and resultant late ABMR.
False positive results of FCXM can occur secondary to the binding of non-specific anti-IgG antibodies to immunoglobulin Fc-receptors on B lymphocytes. The enzyme pronase has been used routinely to remove these receptors, improving the sensitivity and specificity of the crossmatch. In addition, the flow cytometry crossmatch may be transiently positive in patients who have received rituximab therapy.
A false negative virtual crossmatch can arise for a number of reasons. Incomplete typing of the donor, as well as donor specific antibodies in the recipient serum against a unique HLA epitope which is not available on the SAB panel, can give rise to a false negative result.
Patients with positive FCXM and negative Luminex-SAB consider as standard risk, as one study found that the final transplant decision could be taken on the basis of the virtual crossmatch irrespective of the flow cytometry without significant difference in the clinical outcome in those who were flow cytometry positive but virtual crossmatch negative.
In this patient, negative auto crossmatch denies the presence of autoantibodies, so the presence of anti-non HLA antibodies may be an explain for this cross-match. The presence of non-HLA antibodies is also associated with poor graft survival.
If there is the possibility for paired donation, it may be the best solution. If this donor is the only choice, induction therapy with rATG and methylprednisolone pulse and triple immunosuppression maintenance therapy with tacrolimus, MMF and prednisolone is suggested.
Post-transplant surveillance of de novo donor-specific antibodies as well as protocol biopsies, are crucial to facilitate early diagnosis and management of antibody-mediated rejection.
Desensitization has no role in this case.
a
1-A,and E
2-B
3-Band E
1-CDC negative, FC positive ,and negative auto XM and no DSA:
low HLA Ag expression can give negative CDC, or antibodies not fixing complement like some IgG Subtypes. Non-HLA Abs can cause negative FCXM.
2-If not going ahead for Tx, another donor must be arranged otherwise the other option of paired kidney donation.
3-To proceed for Tx with current donor we must proceed for desensitization using plasmapheresis and IVIG ,rituximab ,ATG induction and maintenance with Tac, MMF and prednisolone .DSA must be monitored to predict possible rejection.
4-Desensitization is implemented to achieve negative FCXM.
How do you explain this cross match?
When CDC cross match is negative and FCXM is positive, three options are possible
1- non complement fixing antibody
2- non-HLA antibody
3- low level antibody.
If you decided not to go ahead, what is your alternative?
i will counsell her regarding paired exchnage programm, and benifts of being transplanted with cross match negative .
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
tranplanting pt with postitive FXCM cross match is highly risky even if no dsa is present.
A-as induction immunosuprresion, i will go for atg
b-as maintinace i will go for tac,mmf, pred
What is the role of desensitization in this case?
desentiztion here is to get negative cross match , with iv igg(low or high does centre based prtocols ,plasmapharesis)
Positive FCXM , no DSA , negative auto crossmatch is explained by non HLA antibodies.
Paired exchange donation is an alternative , if another compatible pair is found.
This transplantation is regarded as high risk , and induction therapy with ATG , and maintenance IS with MMF , TAC , steroids is needed.
In this case we need desensitization before transplantation to achieve negative crossmatch then we can proceed with transplantation.
1- How do you explain this crossmatch?
Low level of HLA antibodies/ non-complement fixing Ab/ non-HLA antibodies
2- If you decided not to go ahead, what is your alternative?
Paired exchange donor
3- If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
ATG induction with maintenance Tac +MMF +prednisolone
4- What is the role of desensitization in this case?
Remove these undetected antibodies that may cause rejection especially FCXM is positive
Question? Does analgesic drugs )NSAID) affect FCXM? I do not find the answer
-Mismatch 121
positive FCX
negative Auto cross match
No DSA
Mismatch 121 means 4 mismatch out of six HLA mismatch
positive FCX could indicate the presence of non-complement-fixing or non HLA Ab or low titer antibodies.
a positiveFCX against T-cell and B-cell ndicates the presence of antibodies against HLA class I oragainst HLA class I and II respectively
Therefore it is associated with a higher incidence of rejection and more likely to have poorer graft survival.
-Another alternative option is kidney exchange program
-if we shall procced with this transplantation, in this case she is highly sensitised so desensitisation need to be done by Iv Ig, plasmapheresis and Rituximab
Induction with r ATG and maintenance with tacrolimus , MMF and steroids
-desensitisation is important to have a negative cross match and avoid rejection
Refernce
Ilham MA et al. Clinical Significance of a Positive Flow Crossmatch on the Outcomes of Cadaveric Renal Transplants. Transplantation Proceedings ,Volume 40, Issue 6, July–August 2008, Pages 1839-1843.
How do you explain this cross match?
None HLA antibodies.
If you decided not to go ahead , what is your alternative ?
Paired exchange.
If you decided to go ahead and transplant this lady using donor , what is your immunosuppression protocol ?
As the cross matching of this patient is positive ,her transplant immunosuppressant protocol is similar to those with HLA antibodies and positive cross match including desensitization ,induction and triple TAC.
Angiotensin receptor blockers such as losartan have also been used to block the activity of angiotensin receptor in patients with AT1R-Abmediated rejection . However, a more recent study shows that chronic use of losartan can upregulate AT1R expression resulting in worse outcomes.
What is the role of desensitization in this case ?
To have a negative cross match.
Reference ;
Philogene MC, Jackson AM (2016) Non-HLA antibodies in transplantation:
when do they matter? Curr Opin Organ Transplant 21: 427-432
Kang H., Yoo J.,Lee S.Y., Oh E.J. Causes of Positive Pretransplant Crossmatches in the Absence of Donor-Specific Anti-Human Leukocyte Antigen Antibodies: A Single-Center Experience.Ann Lab Med 2021;41:429-435.
How do you explain this cross match?
The patient has HLA-A one mismatch, HLA-B two mismatches and HLA-DR one mismatch. 4/6 mismatches indicates that this patient will have poor renal allograft outcome in long run. FCXM showed T and B cell positive while auto-crossmatch and DSA not detected. FCXM of T and B cell positive indicates that may be either single or multiple HLA class I donor-specific anti-HLA antibody or a mixture of HLA class I and II donor-specific anti-HLA antibody. Another reason why positive flow crossmatch is likely to positive because by a non-complement fixing antibody, a non-HLA antibody or a low-level antibody. It would be better interpreted with CDC crossmatch and Luminex.
If you decided not to go ahead, what is your alternative?
In view of 4/6 mismatches and positive T cell FCXM, the graft survival is poor. I would suggest patient to get more compatible donor or suggest for paired kidney exchange program.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
This patient will be categorised as highly sensitized patient. I would prefer desensitizing the patient with IVIG and rituximab with plasmapheresis
Then, induction agent will be rATG and maintenance with tacrolimus, MPA and steroids
I would prefer to monitor DSA post transplantation
What is the role of desensitization in this case?
Positive T cell has poor allograft survival. B cell positivity has little role but in combination with T cell, it is significant in determining allograft survival. Desensitization aimed to achieve negative cross match.
References
Mullet, W., Kanellis, J. Understanding cross match testing in organ transplantation : a case based guide for the general nephrologist. Nephrology. Vol 16 issue 2 pp. 125-133.
Abu Jawdeh BG, Cuffy MC, Alloway RR, Shields AR, Woodle ES. Desensitization in kidney transplantation: review and future perspectives. Clin Transplant. 2014 Apr;28(4):494-507. doi: 10.1111/ctr.12335. Epub 2014 Mar 12. PMID: 24621089.
Late ABMR, the latter being commonly defined by its diagnosis beyond 6 months post‐
transplantation, often associated with anti‐HLA DSA, sometimes in the context of under
immunosuppression or nonadherence.
Diagnostic criteria are the detection of typical morphological lesions in the
microcirculation, which include glomerulitis, peritubular capillaritis, transplant
glomerulopathy, serological evidence of circulating DSA and/or the finding of C4d as a
specific marker of DSA‐triggered complement activation in the microvasculature.
1. Summaries the methodology and the conclusion of this study in your own words.
This randomized, placebo-controlled trial.
BORTEJECT] Trial, Bortezomib in Late Antibody Mediated Kidney Transplant Rejection
investigated whether two cycles of Bortezomib (each cycle: 1.3 mg/m2 intravenously on
days 1, 4, 8, and 11) prevent GFR decline by halting the progression of late donor-
specific antibody positive ABMR.
Treatment was associated with gastrointestinal and hematologic toxicity.
There was no significant effect on kidney function, donor specific antibody levels,
rejection phenotypes, or graft survival.
Bortezomib as a single agent may not ameliorate the progression of late rejection.
1. How would you prevent and treat late AMR?
ABMR to high dose steroids and IVIG or steroids and IVIG/rituximab (one dose of
375 mg/m2).
How do you explain this cross match?
Positive FXCM against class I and II antigens, negative CDC and absent DSA can happen in the following conditions:
1- Negative CDC could happen if low HLA antigen on lymphocytes.
2- Negative CDC could happen with some IgG isotypes (IgG2 and IgG4) and IgA because they are not fixed with complement.
3- Non-HLA DSA can produce positive FCXM without DSA.
4- Drugs (like Rituximab, IVIG, and ATG) can be detected as antibodies by FXCM. In this case scenario, there was no history of drug exposure.
5- False negative SAB test.
6- Different serum samples used for SAB and for FCXM.
If you decided not to go ahead, what is your alternative?
Paired Donor Exchange system.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
Desensitization: Plasma exchange, IVIG.
Induction: ATG (Lymphocyte depleting agent)
Maintenance: Tacrolimus, MMF, and Prednisolone.
Follow up: DSA
What is the role of desensitization in this case?
Desensitization role is to get negative flowcytometry crossmatch FCXM, and reduce the chance of Antibody mediated rejection.
Explain cross match
Positive FCXM and no DSA is seen. False negative DSA is possible due to sensitization events. Auto cross match is negative, which means the recipient is not reacting against their own B and T cells.
When CDC cross match is negative and FCXM is positive, three options are possible – either non complement fixing antibody, a non-HLA antibody or a low level antibody.
Low level DSA possible and one or more DSA are not complement fixing. Flow cytometry detects antibodies binding to donor lymphocytes and suggests an increased risk of AMR. They are more sensitive in terms of detection of DSA in comparison with CDC cross matching. Thus, if there is negative CDC cross match then it means that DSA title is low or of a type that does not activate complement.
Positive T cell FCXM suggests there is a DSA to class I antigen while positive B cell FCXM may be due to Class I antibodies or other antibodies directed against class I or II.
Confirmation of presence of anti-HLA antibodies would be done using luminex testing.
Alternative
Alternative options include using an alternative donor, paired kidney donation, blood group incompatible donor option. Paired kidney exchange programme is one where a kidney swap is done in cases when a living kidney donor is imcompatible with their recipient, but does match with another person in the waiting list. This patient has been on the waiting list for 11 years, and there is high possibility for a successful paired kidney exchange to be done.
The degree of risk with each of these options need to be assessed before going ahead with the transplant. Results from antibody detection assays also need to be closely examined and emulated for the best possible outcome post transplant. If low level DSA is the cause of positive FCXM, it may be reasonable to go ahead with the transplant with this donor, but desensitization protocol should be applied to decrease the risk of early rejection of graft.
Immunosuppression protocol if going ahead with transplant with this donor
Induction therapy with ATG
Maintenance therapy – tacrolimus, MMF, prednisone
Desensitization would be done using plasmapheresis and IVIG.
Role of desensitization in this case
Desensitization would be needed in order to make the positive FCXM into negative before the transplant to achieve a better outcome in terms of graft as well as patient well being. It will also drastically decrease the risk of early rejection.
Reference
Mullet, W., Kanellis, J. Understanding cross match testing in organ transplantation : a case based guide for the general nephrologist. Nephrology. Vol 16 issue 2 pp. 125-133.
Abu Jawdeh BG, Cuffy MC, Alloway RR, Shields AR, Woodle ES. Desensitization in kidney transplantation: review and future perspectives. Clin Transplant. 2014 Apr;28(4):494-507. doi: 10.1111/ctr.12335. Epub 2014 Mar 12. PMID: 24621089.
Schinstock, A et al. Current approaches to desensitization in solid organ transplantation. Front Immunol. 11 may 2021. https://doi.org/10.3389/fimmu.2021.686271
How do you explain this cross match?
We need to revise the sensitization history of this lady. If she has a history of sensitizing event , the possibilities are non-complement fixing antibody, a non-HLA antibody or a low-level antibody. If she is not, we need to check the used cut-off values for a positive test1
If you decided not to go ahead, what is your alternative?
To look for an alternative donors or paired kidney donation
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
1. Induction with r ATG as she has positive T cell FCXM
2. Desensitization (IVIG, plasmapheresis and rituximab)
3. Triple therapy: tacrolimus+ MMF+ prednisolone
4. Post transplant follow up with protocol biopsies
What is the role of desensitization in this case?
To convert the T cell FCXM to negative 3
To decrease the risk of AMR associated with non HLA antibodies 4 . A large cohort suggest that non-HLA antigens can affect graft survival. Antibodies to MICA angiotensin II type 1 receptor and endothelial cell antigens are all associated with rejection in some studies 5
1- MULLEY, W. R., & KANELLIS, J. (2011). Understanding crossmatch testing in organ transplantation: A case-based guide for the general nephrologist. Nephrology, 16(2), 125–133. doi:10.1111/j.1440-1797.2010.01414.x
2-A, K., A, M., A, S., M, E. K., & A, H. (2017). An Update on Crossmatch Techniques in Transplantation. Journal of Kidney, 03(04). doi:10.4172/2472-1220.1000160
3-. Kakuta Y, Satoh S, Watarai Y, Aikawa A, Tanabe K, Harada H, Yagisawa T, Ishida H, Okumi M, Takahara S. Successful Desensitization of T cell Flow Cytometry Crossmatch Positive Renal Transplant Recipients Using Plasmapheresis and Super High-Dose Intravenous Immunoglobulin. Transplant Direct. 2017 Nov 28;4(1):e336. doi: 10.1097/TXD.0000000000000753. PMID: 29399625; PMCID: PMC5777667.
4- Pineda, S. & Sigdel, Tara & Chen, Jieming & Jackson, Annette & Sirota, Marina & Sarwal, Minnie. (2018). Pre-Transplant Assessment of AMR Risk by Novel Donor/Recipient Non-HLA Variants. Transplantation. 102. S165. 10.1097/01.tp.0000542798.06175.e6.
5-ait BD, Süsal C, Gebel HM, Nickerson PW, Zachary AA, Claas FH, Reed EF, Bray RA, Campbell P, Chapman JR, Coates PT, Colvin RB, Cozzi E, Doxiadis II, Fuggle SV, Gill J, Glotz D, Lachmann N, Mohanakumar T, Suciu-Foca N, Sumitran-Holgersson S, Tanabe K, Taylor CJ, Tyan DB, Webster A, Zeevi A, Opelz G. Consensus guidelines on the testing and clinical management issues associated with HLA and non-HLA antibodies in transplantation. Transplantation. 2013 Jan 15;95(1):19-47. doi: 10.1097/TP.0b013e31827a19cc. PMID: 23238534.
Absencse of autantibodies and DSAs indicates that The patient might have non HLA antibodies.
I will 1st repeat the FCXM , if repeated with the same results ,I will refuse the donor and refer her to kidney paired donation programs .
If there is no option other than this donor , I would go for desensitization until cross matching is negative, then proceed with thymoglobulin as induction and tacrolimus, MMF and steroids as maintainence regimen
Role of desensitization in non HLA antibodies :
In the form of plasma exchanges, IVIG and retuximab
Until achieving negative cross match
. How do you explain this cross match?
Positive flowcytometery and negative CDC and noDSA:
-low HLA antigen expression on lymphocytes can give negative CDC.
-some IgG isotypes (IgG2 and IgG4) and IgA are not fixed with complement so give negative CDC.
-Positive FCXM and no DSA can be to non-HLA DSA.
If you decided not to go ahead, what is your alternative?
-Either I change the donor or paired exchange kidney program.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
-Desensitisation of this recipient ( plasmapheresis, IVIG)
-Induction with ATG
-Maintenance immunotherapy: Tacrolimus, MMF, prednisolone.
-Close monitoring of DSA.
What is the role of desensitization in this case?
-Desensitization aims to achieve negative FXCM.
Concise and up to point
A positive FCXM accompanied by a negative CDC-XM .
non-complement-fixing or low titer antibodies.
A false positive result can be seen in patients on monoclonal antibody therapy such as
rituximab.
FCXM is more specific than CDC-XM since it can detect specific DSA iso-types like
IgG1, IgG2, and so on. It can also detect complement fixing as well as non-complement
fixing antibodies. Additionally, FCXM detects IgG but not IgM antibodies.
Desensitization protocols, kidney-paired donation, and a combination of both of these
modalities can be used .
Kidney transplantation in this scenario can result in antibody mediated rejection.
First, desensitization protocols are applied to lower the antibody strength to an
acceptable level pretransplantation. Second, an attempt is made to avoid the
unacceptable HLA against which the patient has antibodies through kidney-paired
donation.
For deceased-donor transplantation, patients are awarded extra allocation points and
are enrolled into special programs such as the Acceptable Mismatch Program of
Eurotransplant .
intravenous immunoglobulin (IVIg) (100 mg/kg).
References:
· Sensitized Patients, Transplant, and Transplant Report ,June 2014 .
Hi Dr Sobair, This answer is incomplete.
1- Non HLA Ab
2- paired kidney donations with more suitable, better HLA match and negative FCXM
3- this is a high risk pt as positive FCXM and 121 HLA mismatch, so desensitization with PE and IVIG would be needed.
· Induction with ATG
· maintenance with (Tac, MMF and steroid)
· Monitoring with FXCM and protocol biopsy
4- Desensitization protocol , in general, aim at permitting transplantations of highly sensitized , high immune risk pts and to expand the donor pool .In this case of high sensitization due to non HLA Ab, the aim is to remove and block the action of these alloantibodies that are commonly associated with AMR ( may be accelerated AMR in case of anti endothelial cell receptor Ab ) or with malignant HPN and vascular thrombosis as in case of AT1R Ab . However , data regarding management of Non HLA Ab are limited, so it follow the same recommendations for HLA Ab desensitization with PE, IVIG, Ab depleting agents, B cell depleting and IL 2 blockers.
· Zhang, Qiuheng, and Elaine F Reed. “The importance of non-HLA antibodies in transplantation.” Nature reviews. Nephrology vol. 12,8 (2016): 484-95. doi:10.1038/nrneph.2016.88
Sethi, Supreet et al. “Desensitization: Overcoming the Immunologic Barriers to Transplantation.” Journal of immunology research vol. 2017 (2017): 6804678. doi:10.1155/2017/6804678
Try to structure your answer
A positive B and T cell FCXM in absence of DSA and autoantibodies indicate:
a) Non-HLA antibodies
b) Low level DSA
c) If the DSA is against a historical serum sample and FCXM is done recently, there is a possibility of false-negative DSA on account of newly formed antibodies due to sensitization events occurring post the sample given for DSA.
d) History of use of thymoglobulin/ alemtuzumab. (If only B cell FCXM positive, it may be due to prior use of rituximab)
The alternative is either change the donor or try to look for a paired kidney donor.
As FCXM is positive and 121 HLA mismatch, this is a high-risk transplant.
Patient will require desensitization in form of Plasmapheresis and IVIG to achieve a negative FCXM.
Induction therapy would be Injection ATG
Maintenance immunosuppression in form of Tacrolimus, MMF and steroids.
Post transplant DSA monitoring and protocol biopsy would be required.
Desensitization would be required in a case with positive FCXM to render the crossmatch negative prior to transplant.
V.good for close post TX immune monitoring in this case and protocol biopsy.
negative auto CDXM With positive Tand B FCXM. In patient on long term HD so the possibility of high level of IgM or complement factor C1q which can compete and bond to saturate antigen beads and give false negative result of the SAB lumenix test
Prozone effect or hook effect
False positive FCXM also due to nonHLA AB so to improve the sensitivity and specificity of FCXM especially in the presence of negative autoCDXM we need to add pronase enzyme to digest the fc receptors of the donor lymphocytes and overcome the non specific AB binding
This patient if confirmed positive FCXM with 5 mismatches better to ask for Pair exchange. Program. Also ask for more specific epitope based matching assay to overcome the false positive results during the traditional HLA matching assay
If I’m going ahead with the transplant from this donor. Can go first with desensitization with plex and IVIG. Followed by rituximab repeat FCXM and if negative and no DSA Will use ATG as induction IS. Followed. By Triple Maintenace IS including tacrolimus MMF , steriod with close monitoring with DSAs
References :
Up to date medicine desensitization in kidney transplantation access 2021.
2- crossmatch strategies in renal transplantation: practical guide for the practicing clinician,Nalaka Gunawansa,RoshniRathore,Ajax Sharma and Ahmed Halawa, Journal of Transplant Suregery2017,volume1/:8-15.
If you finally conclude they are non HLA antibodies what is their role (effect) in SOT.
How do you explain this cross match?
It could be due to non HLA antibodies.
If you decided not to go ahead, what is your alternative?
To find a more compatible donor through paired donation.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
After desensitization with IVIG + PP and may be Rituximab, induction IS with ATG and maintenance therapy with TAC, MMF and steroids.
What is the role of desensitization in this case?
To have a negative crossmatch.
Reference:
Fine but please try to find out about the role of nonHLA antibodies in SOT.
Research on HLA identical transplants showed that the recipient still have a risk of graft loss, based on this fact, researchers looked for non HLA antibodies that can cause rejection in HLA identical pairs. Non HLA antibodies are known to cause ABMR and graft loss, the problem with them is that overview of treatment option for these antibodies are still lacking, most reports showed positive effect on graft outcome by removing non HLA antibodies, however monitoring of non HLA antibodies level after treatment and standardization of therapies is still needed.
Examples of non HLA antibodies:
MICA, anti-endothelial cell antibodies, antibodies against GBM, antibodies to PLA2R, autoantibodies to vimentin and myosin, antibodies to collagen I, collagen V, and K-alpha tubulin.
Reference:
Kardol-Hoefnage T., Otten HG. A Comprehensive Overview of the Clinical Relevance and Treatment Options for Antibody-mediated Rejection Associated With Non-HLA Antibodies.Transplantation.2021 July;105(7): 1459-1470.
How do you explain this cross match?
We have HLA mismatch 121 at HLA A, B and DR, FCXM is positive for T cells and B cells(that mean there are antibodies against class I and II), auto cross match is negative excluding auto antibodies with no DSA with Luminex SAB.
-Causes of positive T and B FCXM with negative SAB (no DSA):
1-Non HLA IgG binding to binding to cell service antigens on lymphocytes
2-Drug interference where therapeutic antibodies bind to lymphocytes and detected by FCXM as antibodies (like ATG, Rituximab ,IV IG)>>there is no medication history in the mentioned scenario.
3-Different serum samples used for SAB and for FCXM
4-false negative SAB test
If you decided not to go ahead, what is your alternative?
Alternative will be wait for another suitable donor with negative FCXM or looking for paired kidney exchange.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
Basically ,I want to know how far she is sensitized by doing PRA and she will need to repeat FCXM to rule out the false positive probability and if came positive proceed for desensitization with PP and Rituximab followed by induction with lymphocyte depleting agent (high immunologic risk of more than one HLA mismatch, level of PRA??)
For maintenance immunosuppression to use conventional triple immunosuppression of prednisolone ,MMF and CNI
What is the role of desensitization in this case?
Desensitization to change FCXM from positive to negative so can proceed for transplantation.
good
Drug interference where therapeutic antibodies bind to lymphocytes and detected by FCXM as antibodies (like ATG, Rituximab , IV IG)
Q? please
why we give IV IG for desensitization if it can be detected by FCXM ? I can not imagine it
How do you explain this cross match?
FCXM is positive for both B and T cells, The auto-crossmatch is negative and No DSA was found. this indicates that the patient has non-HLA antibodies.
If you decided not to go ahead, what is your alternative?
the option of paired exchange will be a good choice. if the patient has no other option and this is the only donor available, he should go for desensitization until the cross match is negative especially if the strength of flow crossmatch MCS is high > 250.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
The patient should go for desensitization before transplantation. then induction ATG and maintenance(tacrolimus, MMF and steroid).
perform pretransplant HLA desensitization using a combination of high-dose IVIG and rituximab in most patients. desensitization with this protocol has been shown to reduce mean PRAs, decrease flow cytometry crossmatch median channel shift (MCS), and shorten the time to transplantation, permitting transplantation in approximately 75 to 80 per cent of patients.
–Desensitization is considered successful if the patient has an acceptable crossmatch, which is defined as negative flow cytometry crossmatch, or a positive flow cytometry cross matches with MCS ≤250.
If the results of the crossmatch are acceptable, transplant surgery is performed within one week. If the results of the crossmatch are not considered to be acceptable, either pursue alternative desensitization therapies or enrol the patient in kidney paired donation (KPD).
Your description of desensitization is OK but the role in nonHLA antibodies is still controversial.
How do you explain this cross match?
Positive FCXM for both B and T cells but no detected DSA beside negative Auto-crossmatch ruling out both HLA-Antibodies and auto-antibodies (IgM) respectively. This cross-match goes with Non-HLA Antibodies eg; anti-endothelial cell antibodies (AECA),Angiotensin type 1 receptor (AT1R),Perlecan antibodies, . Previous exposure to thymoglobulin and Rituximab gives the same crossmatch pattern but nothing in the patient scenario points toward this.
If you decided not to go ahead, what is your alternative?
Her 1-2-1 mismatch carries high risk of rejection and poor graft survival.
The alternative to this risky donation is the exchange or Paired kidney Donation.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
What is the role of desensitization in this case?
The desensensitization regimens( eg; plasmapheresis and IVIG) have no clear evidence of effectiveness in non-HLA antibodies removal.(1)
Referrences
Why Bortezomib but not ATG or Campath
How do you explain this cross match?
FCXM is positive for both B and T cell which implies that the patient has probably anti-HLA class II antibodies. The auto-crossmatch is negative which means that the antibodies are not IgM antibodies as in autoimmune disease. There was no DSA detected. The DSA result is either explained by low DSA level or non-HLA antibodies.
The role of non-HLA antibodies in kidney transplantation is still controversial in DSA negative recipients.Non –HLA antibodies as AT1R-Ab, MICA-Ab, ETAR-Ab or EC-XM+ are rarely found among ABM rejection DSA neg patients. One study reported that non- HLA auto-antibodies could have role in DSA positive. However they found that they could not explain ABMR DSA neg.
Another study showed that autoantibodies can mediate graft damage via complement-dependent and complement-independent pathways. Incomplete knowledge of the autoantigens that elicit immune responses during transplantation hampers the diagnosis and treatment of AMR.
A study published in JASN showed that the production of autoantibodies in association with renal damage that may occur post-transplantation, at the time of rejection, at the time of transplantation, or before transplantation and in association with ischemia-reperfusion injury is emerging as an important contributor to the risk of renal dysfunction.
If you decided not to go ahead, what is your alternative?
HLA mismatch is 121 which is considered a high risk for rejection mandating aggressive induction and maintenance therapy. Paired kidney Donation is acceptable alternative for this patient, or another kidney donor offer is also an option.
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
The patient is at high risk of rejection given the high mismatch , and taking in consideration positive crossmatch. So induction therapy should be appropriate for the high risk. Induction therapy with r-ATG with maintenance therapy CNI bases/MMF/steroids.
Given the positive crossmatch with negative DSA, the patient has likely preformed non-HLA DSA. The risk of non-HLA antibodies is increased with prolonged cold ischemia period, so our approach to minimize the cold ischemia to avoid ischemia reperfusion injury.
What is the role of desensitization in this case?
Role of desensitization in the settings of negative DSA, is controversial if non-HLA antibodies are suspected desensitization protocols increase the risk of infection and the presence of non-HLA antibodies may increase the risk of rejection.
Desensitization is not standardized for DSA negative non-HLA positive antibodies.
References
Héloise Cardinal, Mélanie Dieudé and Marie-Josée Hébert. The Emerging Importance of Non-HLA autoantibodies in Kidney Transplant Complications.JASN February 2017, 28 (2) 400-406
Qiuheng Zhang , Elaine F. Reed. The importance of non-HLA antibodies in transplantation. Nat Rev Nephrol. 2016 Aug; 12(8): 484–495.
Marta Crespo, Laura Llinàs-Mallol, Dolores Redondo-Pachón et al. Non-HLA Antibodies and Epitope Mismatches in Kidney Transplant Recipients With Histological Antibody-Mediated Rejection. Front. Immunol., 06 July 2021
Thankyou for the explicit survey of the role of nonHLA antibodies in Tx.
How do you explain this crossmatch?
If you decided not to go ahead, what is your alternative?
If you decided to go ahead and transplant this lady using this donor, what is your immunosuppression protocol?
What is the role of desensitization in this case?
REFERENCES
1. Kuten S, Patel S, Land G, Eagar T, Knight R, Loucks J, Gaber L, Gaber A. Impact of Positive Crossmatch Due to Non-HLA Antibodies on Graft Outcomes in Renal Transplantation [abstract]. Am J Transplant. 2015; 15 (suppl 3).
In IRI is there a role for production of nonHLA antibodies post operatively?
is there an augmentation role in ABMR played by existing nHLA antibodies?
Then there is a role for desnsitisation.
Please to my comments to Ahmad Aref
cross match positive B and T cell in absence of DSA:
1- non HLA antibodies
2- too low DSA
alternative is paired donor transplant
immunosuppressive protocol :
1-desensitization by plasmapharesis and ivig
2- induction with ATG
3- maintenance with tacrolimus, MMF, steroid
4- follow up of DSA post transplant
role of desensitization is to achieve negative crossmatch
very concise but correct.