HLA Antibodies and Their Role in Graft Loss. What s New? What Matters? What s Next? Immune Response Against HLA Sensitization. Pregnancy.

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1 HLA Antibodies and Their Role in Graft Loss What s New? What Matters? What s Next? Immune Response Against HLA Sensitization Pregnancy Transfusion Allograft α 2 C HLA C HLA α Antibody 3 Lee Ann Baxter-Lowe, Ph.D. Immunogenetics and Transplantation Laboratory Crossreactivity with other antigens Crossmatch Detects HLA Antibodies Donor Cells and Recipient Serum HLA Cytotoxicity (CDC) C1 Cell Death Viable Donor Lymphocyte Recipient Serum Antibody Binding C Complement Binding Dye Score Dead Cells 1, 2, 4, 6, 8 Crossmatch Positive Negative Yes 24 8 Rejection No % 4% 1

Crossmatch Detects HLA Antibodies Donor Cells and Recipient Serum HLA-A1 Major Advance: Microparticle Arrays Flow Cytometry Crossmatch HLA Serum Luminex 1 8 HLA-A2 Viable Donor Lymphocyte Recipient

2 Crossmatch Detects HLA Antibodies Donor Cells and Recipient Serum HLA-A1 Major Advance: Microparticle Arrays Flow Cytometry Crossmatch HLA Serum Luminex 1 8 HLA-A2 Viable Donor Lymphocyte Recipient Serum Antibody Binding Detection Antibody Binding % of Max Flow Cytometer MCS or MESF Microparticle Array Antibody Binding MFI Interpretation Three Formats for Microparticle Arrays Test Screen HLA Source 3-4 individuals Result Pos/Neg Single Antigen Reagents Determine Specificity and Strength PRA 1 individual PRA MFI Single Antigen 1 HLA Molecule Specificity Strength A*21 A*26 A68 A69 2

3 MFI Classification of Antibodies Using Single Antigen Reagents High Risk: >85 Moderate Risk: Low Risk: Very WeaK: Virtual Crossmatch HLA Antibody Data Used to Predict Crossmatch Result Viable Donor Lymphocyte Recipient HLA Antibodies A2, A68, A69 Donor 1 A1,2;B8,44;DR2,17 Positive Donor 2 A1,3;B8,44;DR2,17 Negative High Rejection Risk Donors Can Be Excluded Results: Mean Waiting List Time Unacceptable Antigens Increased Risk Antigens Com p 1 75 p<.1 by Newman-Keuls test Days 5 MFI 25 Crossmatch No Anti-HLA Abs Flow Cytometry No Anti-HLA Abs Anti-HLA Abs (12/98-3/1) (12/98-3/1) Anti-HLA Abs (4/1-7/3) (4/1-7/3) p<.1 based on ANOVA test Cedars-Sinai Health Systems HLA Laboratory Appel J, Reinsmoen NL, Davis RD, et al., Transplantation 25: 153, 26 3

Results: Waiting List Mortality UNOS cpra Calculator Mortality (%) 5 4 3 2 p=.7 by Fisher s exact test p=.

4 Results: Waiting List Mortality UNOS cpra Calculator Mortality (%) p=.7 by Fisher s exact test p=.47 by Fisher s exact test 1 Crossmatch No Anti-HLA Abs Flow Cytometry No Anti-HLA Abs Anti-HLA Abs (12/98-3/1) (12/98-3/1) Anti-HLA Abs (4/1-7/3) (4/1-7/3) Appel J, Reinsmoen NL, Davis RD, et al., Transplantation 25: 153, 26 Cedars-Sinai Health Systems HLA Laboratory Calculated PRA (cpra) % deceased donors with unacceptable antigens Unacceptable Antigens A2 A2 A68 A69 A8 DR4 A2 DR4 Bw6 cpra 47% 53% % 29% 6% 8% 4

5 cpra Impacts Organ Allocation Kidney >2% national allocation of -Ag MM Donors >8% 4 years waiting time Heart/Lung Virtual crossmatch aids in regional allocation Number of Positive Crossmatches Reported as a Reason for Organ Refusal 4, 35, 3, 25, 2, 15, 1, 5, Allocation PRA/CPRA: OPTN Deceased Donor Kidney Match Runs Only 28,144 27,717 15,579 2,724 7/1/21-12/31/21 1/1/22-6/3/22 4/1/29-9/3/29 1/1/29-3/31/21 /Not Reported Histocompatibility Committee Data Report Deceased Donor Kidney Transplants by Era and Recipient s Sensitization Level Can Risk Assessment Be Refined? 1% 9% Percentage of registrations 8% 7% 6% 5% 4% 3% 2% 1% % OPTN 7/1/21-12/31/21 1/1/22-6/3/22 4/1/29-9/3/29 1/1/29-3/31/21 Allocation PRA/CPRA: /Not Reported Histocompatibility Committee Data Report Gloor et al AJT 21 5

6 HLA Antibodies Are Associated with AMR Figure 2. The presence of HLA-s on the highest rank pregraft serum associates with a significantly decreased graft survival (A), regardless of whether HLA-s were class I or II (B) Negative Crossmatch FCM <3 FCM >3 Positive CDC P<.1 No <1, >1, P<.1 Lefaucheur, C. et al. J Am Soc Nephrol 21;21: Gloor et al AJT 21 Copyright 21 American Society of Nephrology Figure 3. Peak HLA- MFIs are better predictors of acute AMR than current HLA- MFIs Weak Donor-Specific HLA Antibodies Before Transplant Are Associated with Poor Outcomes HLA Ab % ACR % AMR 3 yr DCGS 3 yr CrCl 3 yr PS +/FXM (n=19) +/FXM (n=16) Unsensitized (n=178) P =.1 P =.6 P =.1 Lefaucheur, C. et al. J Am Soc Nephrol 21;21: Thymoglobulin induction Copyright 21 American Society of Nephrology Dunn et al ATC 21 CNI/ MMF/ rapid discontinuation prednisone 6

7 Levels of HLA Expression Are Associated in Significant Differences in Relationship of MFI and FCXM (MESF) High Thousands HLA Class I p<.1 High Low Thousands Total MFI for Expression Level Thousands High Low HLA Class II p< Thousands Greater than 1 st. deviation above the mean Low Lower than 1 st. deviation below the mean HLA Levels Influence Crossmatches HLA Class I (n=75) HLA (mean MESF) Ratio (MESF/MFI) HLA Class II (n=73) HLA (mean MESF) Ratio (MESF/MFI) Low 15, 1.1 Low 12, 1.9 High 388, 3.4 High 154, 2.7 Ratio p= p=.38 Weak Antibodies Are Risk Factor for Memory Response Pre Transplant Heart: Pre- and Post-Transplant HLA Antibodies Are Detrimental Post Transplant Ho et al Human Immunology 29 7

8 Kidney: After Transplant Antibody Specificity and Strength Impact Graft Survival Time to de novo antibody among all patients Failure group MFI<1 MFI:1-5 MFI>5 Control group Years Posttransplant Terasaki et al AJT 27 Zhu, Terasaki, et al. Clinical Transplants 28, p.184 Lung: Treatment Improves Survival Death-Censored Allograft Survival Death-Censored Allograft Survival p <.1 p =.21 Time from Transplantation (Months) Time from Transplantation (Months) Everly MJ et al, Am J Transplant. 29; 9: Hachem et al JHLT 21 8

9 Kidney Graft Survival by Transplant Era Deceased Donors Graft Survival 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Cecka, Clinical Transplants 28, p N 37,327 38,377 42,7 T 1/ P< Years Posttransplant 25 HLA Antibodies and Their Role in Graft Loss What s New? What Matters? What s Next? Technology HLA Antibodies Play a Key Role in Outcome Effective Treatment Graft Survival (%) Heart Graft Survival by Transplant Era N 17,414 11,732 14,76 p< Years after Transplantation Figure 4. The graft survival in patients with preexisting HLA- MFIs >3 is significantly lower than in patients with HLA- MFIs <=3 Lefaucheur, C. et al. J Am Soc Nephrol 21;21: Everly, Clinical Transplants 28, p. 38 Copyright 21 American Society of Nephrology 9

10 Antibody-Mediated Microcirculation Injury Is the Major Cause of Late Kidney Transplant Failure ATN, TCMR, CNI, etc. C4d Pos ABMR C4d Neg ABMR Recurrent GN Einecke et al AJT 29:

Guideline CHAPTER 2. IMMUNOLOGICAL WORK-UP OF KIDNEY DONORS AND RECIPIENTS. GdL COLLEGIO SIN-SITO

Nephrol Dial Transplant (2013) 28: ii1 ii71 Guideline CHAPTER 2. IMMUNOLOGICAL WORK-UP OF KIDNEY DONORS AND RECIPIENTS GdL COLLEGIO SIN-SITO Coordinatore: Cozzi Amoroso, Cardillo, Nocera, Piazza, Rombolà,