DQB1 antigen matching improves rejection-free survival in pediatric heart transplant recipients

Background: Presence of donor-specific antibodies (DSAs), particularly to class II antigens, remains a major challenge in pediatric heart transplantation. Donor-recipient human leukocyte antigen (HLA) matching is a potential strategy to mitigate poor outcomes associated with DSAs. We evaluated the hypothesis that antigen mismatching at the DQB1 locus is associated with worse rejection-free survival.

Methods: Data were collected from Scientific Registry of Transplant Recipients for all pediatric heart transplant recipients 2010-2021. Only transplants with complete HLA typing at the DQB1 locus for recipient and donor were included. Primary outcome was rejection-free graft survival through 5 years.

Results: Of 5,115 children, 4,135 had complete DQB1 typing and were included. Of those, 503 (12%) had 0 DQB1 donor-recipient mismatches, 2,203 (53%) had 1, and 1,429 (35%) had 2. Rejection-free survival through 5 years trended higher for children with 0 DQB1 mismatches (68%), compared to those with 1 (62%) or 2 (63%) mismatches (pairwise p = 0.08 for both). In multivariable analysis, 0 DQB1 mismatches remained significantly associated with improved rejection-free graft survival compared to 2 mismatches, while 1 DQB1 mismatch was not. Subgroup analysis showed the strongest effect in non-Hispanic Black children and those undergoing retransplant.

Conclusions: Matching at the DQB1 locus is associated with improved rejection-free survival after pediatric heart transplant, particularly in Black children, and those undergoing retransplant. Assessing high-resolution donor typing at the time of allocation may further corroborate and refine this association. DQB1 matching may improve long-term outcomes in children stabilized either with optimal pharmacotherapy or supported with durable devices able to await ideal donors.