Aim: HLA matching leads to increased graft survival for most kidney recipients. In earlier studies, recipients with rare HLA phenotypes were not as well matched with their donor due to differences between deceased donor pool and recipient population. In this contemporary, single center cohort, we reevaluate the frequency of HLA matching in different ethnic groups and their impact on development of donor-specific HLA antibodies (DSA).
Methods: HLA-ABDR antigen-level mismatches were obtained from our LIS for kidney transplants at VCU from October 1, 2021-April 15, 2025. Patients with an unknown/undisclosed ethnicity or an ethnicity listed as “other” were excluded. Mismatches were counted at the split antigen level, IE. A23 would not match A24. The prevalence of DSA was also evaluated for this cohort. This was compared to national data in the Standard Transplant Analysis Registry (STAR) file for deceased donor kidney transplants from October 1, 2021- December 24, 2024. For these data, we excluded donor/recipient pairs with unknown race/ethnicity and/or missing HLA typing.
Results: White kidney recipients were significantly more likely to receive a better matched graft, both at the single center level (p=0.0008) (Figure 1A/B), and at the national level (p < 0.0001) (Figure 2). 39% of black, 32% of Asian, and 50% of Hispanic recipients had DSA as compared to 26% of white recipients. Of patients with DSA, 33% of black recipients had 6 ABDR MM, as compared to 10% of white recipients. The most prevalent antibody in this cohort was directed against DQ antigens, with 50% of black, 45% of white, and 62% of Asian recipients who developed DSA expressing a DQ antibody.
Conclusion: White recipients are more likely to receive a well-matched graft and less likely to develop DSA. Crossing the HLA barrier increases the risk of antibody development and may disproportionately impact transplant recipients from minority populations with rare HLA phenotypes. HLA matching plays a large role in the current kidney allocation system, providing both points and higher allocation sequences to potential transplant recipients. A variable of “likelihood of a match”, such that patients whose HLA antigens which are hard to match are given more priority points when a matched deceased donor offer is run, could increase equity in deceased donor kidney transplantation. Future research will explore an algorithm to calculate percent likelihood of 0 ABDR mm for a given candidate.
