HLA matching between donors and recipients improves clinical liver transplant graft survival

The importance of human leukocyte antigen (HLA) matching between liver transplant donors and recipients on graft survival remains unclear and is not a clinical consideration in liver transplantation. This study aimed to determine the relationship between HLA matching and liver graft survival using a large-scale multi-centre database (UNOS/OPTN) and multivariate logistic analysis. The secondary aim was to determine whether this relationship was influenced by transplant indication and donor status.

This retrospective observational analysis was performed using 22 702 liver transplant recipients from the UNOS/OPTN database. Patients were divided into two groups based on number of HLA mismatches (0-3 mismatches vs. 4-6 mismatches) and then subcategorized by indication and donor status. Risk-adjusted outcomes were assessed by multivariate Cox analysis adjusting for donor and recipient characteristics and visualized using Kaplan-Meier survival curves.

Allograft survival and risk of acute rejection were associated with degree of HLA mismatch. This association between HLA mismatch and graft survival persisted in individuals who underwent transplant for hepatitis, metabolic, drug toxicity, and congenital indications. Donor status also influenced the relationship between HLA mismatch and graft survival. Graft survival in DBD recipients was longer than in DCD in the 4-6 HLA mismatch group, whereas no significant difference was found in the 0-3 HLA mismatch group.

HLA mismatch significantly reduced graft survival and increased risk of acute rejection. This association was noted only in specific indications. These findings are of potential clinical relevance to organ allocation, allograft matching algorithms, immunosuppression protocols, and transplant surveillance.