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RENAL TRANSPLANTATION INTO HIGH RISK, HIGHLY SENSITIZED RECIPIENTS: A SINGLE CENTER EXPERIENCE

RENAL TRANSPLANTATION INTO HIGH RISK, HIGHLY SENSITIZED RECIPIENTS: A SINGLE CENTER EXPERIENCE. Randy Hennigar PhD, MD Director, Nephropathology and Electron Microscopy Emory University Hospital Atlanta ,GA. Incidence of C4d in Renal Transplant Population: Emory University Hospital (EUH).

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RENAL TRANSPLANTATION INTO HIGH RISK, HIGHLY SENSITIZED RECIPIENTS: A SINGLE CENTER EXPERIENCE

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  1. RENAL TRANSPLANTATION INTO HIGH RISK, HIGHLY SENSITIZED RECIPIENTS: A SINGLE CENTER EXPERIENCE Randy Hennigar PhD, MD Director, Nephropathology and Electron Microscopy Emory University Hospital Atlanta ,GA

  2. Incidence of C4d in Renal Transplant Population: Emory University Hospital (EUH) • Objective: To gain more information about the role of antibody mediated rejection in the renal transplant population @ EUH. • Method: From Nov 2003 to Mar 2005, a total of 313 consecutive biopsies (252 tx patients) were screened for C4d deposition. Bxs were performed for renal dysfunction.

  3. Immunoperoxidase Staining for C4d

  4. Incidence of C4d in Various Renal Tx Populations Modified from Bohmig & Regele, Transpl Int 16:773, 2003

  5. Incidence of C4d in Renal Transplant Population @ EUH • Results: 23 of 252 pts (9%) were positive, using the criteria of Nickeleit and Mihatsch (Nephrol Dial Transpl 18: 2232-2239, 2003). • Conclusion: The incidence of C4d deposition (and presumably antibody-mediated rejection) among the kidney transplant population at EUH appears less prevalent than that reported in the literature.

  6. ????

  7. Emory University Hospital:Renal Transplant Center Activity (2004) Deceased donor txs = 111 (74%) Living donor txs = 39 (26%) Total = 150 Tx rate among waitlist pts = 0.3 From: The Scientific Registry of Transplant Recipients

  8. Emory University Hospital:Transplant Recipient Characteristics (2004) Ethnicity/race of waitlist pts (end of 2004): EUH(%)USA average(%) African-American 63 36 White 32 39 Hispanic/Latino 2 16 Asian 3 8 Other <1 1 From: The Scientific Registry of Transplant Recipients

  9. Emory University Hospital:Transplant Recipient Characteristics (2004) Ethnicity/race of tx patients (deceased donors): EUH(%)USA average(%) African-American 52 30 White 45 49 Hispanic/Latino 1 14 Asian 2 6 Other 0 2 From: The Scientific Registry of Transplant Patients

  10. Panel Reactive Antibodies (PRA) • A screening mechanism to determine the HLA antibody profile of potential transplant recipients. • Periodic screening (monthly/quarterly) of recipient sera with a panel of HLA-typed cells. • Sensitization of the recipient is expressed as the percentage of serum reactivity with the total panel. Typically, high PRA is indicative of a highly sensitized recipient- one who is at risk for early graft loss.

  11. Deceased Donor Renal Transplants (1999 – 2004)

  12. Emory University Hospital:Peak PRA Prior to Deceased Donor Renal Tx (2004) • From: The Scientific Registry of Transplant Recipients

  13. Cadaveric Renal Allograft Survival (1998 – 2003) 99 100 97 Emory N = >500 90 94 93 90 UNOS N = 20791 80 81 % Graft Survival 70 60 50 3 mos 0 1 2 3 Years UNOS/SRTR 2003

  14. Evolution of HLA Antibody Detection Anti-HLA Antibody Ly Ly Ly Ly Ly Ly Ly Ly Anti-Human Globulin Fluorescenated Anti-Human Globulin C1 C1 Membrane Attack Complex Membrane Attack Complex Dye Dye Ly Ly or CD19 (B cell) CD3 (T cell) Flow Cytometer Cytotoxicity Enhanced Cytotoxicity Flow Cytometry Bray et al Immunol Res. 29:41, 2004

  15. From: Gebel et al. Am J Transpl 3:1488-1500, 2003

  16. From: Gebel et al. Am J Transpl 3:1488-1500, 2003

  17. Impact of HLA Antibodies Detected Only by Flow Cytometric Crossmatch (Regrafts)Gebel et al. Am J Transpl 3:1488-1500, 2003

  18. In 2002, of the >150 labs participating in the ASHI-CAP class I crossmatch surveys (MX1-A, B, C), only 68–70% reported AHG augmented CDC and 47–52% flow-based crossmatches.

  19. From: Gebel et al. Am J Transpl 3:1488-1500, 2003

  20. Perceived Pitfalls of Flow Cytometry Crossmatching (FCXM) • Too sensitive • Detection of low titer and noncomplement-fixing antibodies of little or no clinical relevance • Would inappropriately deny a patient access to transplantion • Does not reliably predict poor clinical outcomes

  21. IgG FCXM:Renal Allograft StudyFrequency of rejection in a single center 44% 40% n = 56 n = 41 81% vs83% 1 yr survival % rejection FCXMs ARE IRRELEVANT! IgG Kerman et al Transplantation 68:1855-1858, 1999

  22. In 2002, of the >150 labs participating in the ASHI-CAP class I crossmatch surveys (MX1-A, B, C), only 68–70% reported AHG augmented CDC and 47–52% flow-based crossmatches.

  23. Panel Reactive Antibodies (PRA) • A screening mechanism to determine the HLA antibody profile of potential transplant recipients. • Periodic screening (monthly/quarterly) of recipient sera with a panel of HLA typed cells. • Sensitization of the recipient is expressed as the percentage of serum reactivity with the total panel. Typically, high PRA is indicative of a highly sensitized recipient- one who is at risk for early graft loss. • Historically, PRA has been antigen-nonspecific.

  24. Antigen Specific Antigen Non-Specific METHODS FOR ANTIBODY EVALUATION Complement-dependent Cytotoxicity (CDC): - Direct CDC (Standard CDC) - Modifications Washes Extended Incubation Anti-human globulin (AHG-CDC) DTT / DTE Flow Cytometry (cells): - T cell / B cell - Pronase ELISA - Yes / No - PRA % (I & II) - Specificity (I & II) “FlowPRA” Flow cytometry using microparticles (“beads”) - PRA % (I and II ) - Specificity (I & II) Multi-plex - Suspension Arrays - Protein Chips

  25. Flow Microparticles One Lambda www.onelambda.com

  26. Solid Phase, Antigen-Specific Assays Extract and Purify HLA Antigens B cells + EBV Class I or II Phenotype or Individual Molecule Flow Cytometry Microparticles Purified HLA Antigens ELISA

  27. 90% Microparticles ELISA Coated with 30 HLA I or 30 HLA II antigens

  28. Table 6. Flow PRA versus AHG-CDC PRA (n = 203) Flow PRA-NegativeFlow PRA-Positive AHG-CDC PRA >10% 2 7 AHG-CDC PRA <10% 160 34

  29. PRA ANALYSIS BY DIFFERING METHODLOGIES POSITIVENEGATIVE CDC 102 162 AHG-CDC 116 (+13%) 148 ELISA 127 (+10%) 137 FlowPRA 139 (+10%) 125 Gebel and Bray, Transplantation 69:1370-1374, 2000.

  30. Positive FCXM are associated with graft loss when FlowPRA detects high levels of HLA antibodies 30 20 8 % Graft Survival 7 12 20 Bray RA, Nickerson PW, Kerman RH, Gebel HM. Immunol Res. 29:41, 2004

  31. P > 0.05 Cutpoint = 30% Renal Transplantation (DD) into High vs. Low PRA Patients with Negative FCXM N = 372 N= 492 N = 120 Submitted for publication

  32. Antibody Negative Crossmatch Negative Antibody Negative Crossmatch Positive Antibody Positive Crossmatch Negative Antibody Positive Crossmatch Positive Antibody Paradigms - 2005 Screening Crossmatch Low Risk High Risk

  33. PRA • PRA can be a qualitative and/or quantitative • assessment of alloimmunization in transplant • patients. • Optimally, PRA testing should identify the • specificity of an antibody and provide the • “transplantability” index of a patient. • More succinctly, PRA testing should correlate • with the final crossmatch.

  34. CLASS II DONOR SPECIFIC ANTIBODIES ARE PATHOGENIC IN PRIMARY RENAL ALLOGRAFTS Nickerson et al AJT: 4(8) 257, 2004 Impact of Donor Reactive HLA Antibodies Rejection Time to Ab mediated Time to First Month Rejection Graft Loss Graft Loss Donor Reactive Class I 14/15 (93%) 6 (1-17) 4 (27%) 4 (1-14) Donor Reactive Class II 8/10 (80%) 5 (2-7) 3 (30%) 5 (2-9) HLA Ab (non-donor) 3/21 (14%) 13 (13-19) 0 (0%) NA

  35. BCM+ class II, n=14 BCM+ autoAb, n=10 BCM+ Ab UNKNOWN, n=38 BCM-,n=930 Le Bas-Bernardet,et al Transplantation 75:477,2003 77% of positive B cell crossmatches ARE NOT DUE to HLA antibodies!

  36. Transplant across a + crossmatch anticipating Immunosuppression Approaches Pharmacological Biological Desensitization IVIG PP / IVIG Rituxan Identical Sibling Xenotransplantation Acceptable Mismatch - Detailed Antibody Analysis - Comprehensive PRA - Virtual Crossmatch

  37. Acceptable Mismatches Putative Recipient: A1, A30; B7, B8 ; DR11, 15 Antibodies - A2, 23, 24, 68 Potential Donor: A25, A33; B42, B18; DR12, DR13

  38. Strategic Approaches - Based on recognition that matching is not for everyone- 85% of DD Txs are mismatched. - Focus on appropriate mismatching rather than looking for an HLA “match”. - Requires detailed evaluation of the patient’s HLA antibodies. - Shifts emphasis to antibody evaluation and away from crossmatching to identify acceptable mismatches.

  39. Desensitization Protocols Aren’t For Everyone - High Titer HLA Antibodies >512 - Refractory Specificities DR52, DR53 - Fragile Patients - Restricted to Living Donors - $$$$$$$$$$$$s

  40. Recommendations to define the ‘non-sensitized’ patient: • Validate patient history for the lack of sensitizing • events. • Confirm that a patient is nonsensitized using a solid • phase assay documented to be more sensitive than • CDC assays.

  41. Recommendations to evaluate the ‘sensitized’ patient: • To optimize detection of low titer HLA antibodies, • monitoring should be performed using sensitive • solid-phase assays. • Monitoring should include evaluation for both • antibodies to class I and class II HLA antigens. • A crossmatch test must be performed before • transplantation using, as a minimum, an enhanced CDC • technique. • The final crossmatch technique should be of equal • sensitivity to the solid-phase assay used to screen for the • presence of HLA antibody. • A B-cell crossmatch should be included in the final • crossmatch. • Peak sera should be included in the final crossmatch. • Auto-crossmatches should be utilized to aid in the • interpretation of allo-crossmatches.

  42. END OF LECTURE

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