Class II HLA Eplet Mismatch Is a Risk Factor for De Novo Donor-Specific Antibody Development and Antibody-mediated Rejection in Kidney Transplantation Recipients.

OBJECTIVES: We investigated the correlation between class II HLA epitope mismatch and antibody-mediated rejection (AMR) episodes in kidney transplant recipients. In patients with AMR, epitope mismatch was also examined for each class II HLA mismatch to determine development of de novo donor-specific antibodies (DSAs).

METHODS: We conducted a retrospective study of 167 kidney recipients. The numbers of eplet mismatches were compared between those with (n = 12) and without (n = 155) AMR, and the numbers of eplet mismatches for each type of mismatch in class II HLA among the AMR patients was also compared.

RESULTS: Twelve AMR episodes were diagnosed. The total number of eplet mismatches in AMR patients with either HLA-DR or HLA-DQ was greater than those in non-AMR patients (P = .0085 and P = .0041, respectively), though the incidence of HLA class II (DRB1 + DQB) mismatch was not significantly different between the groups (P = .095). The rate of non-AMR status in patients with ≥15 was lower than those with <15 HLA class II (DR or DQ) eplet mismatches (P = .0299 and P = .0128, respectively). Twelve AMR patients had 30 HLA-DRB1/3/4/5 and 32 HLA-DQA/B mismatches. In both HLA-DR and -DQ, de novo DSAs developed against HLAs in association with a greater number of eplet mismatches (P = .0046 and P = .0044, respectively).

CONCLUSION: Class II HLA eplet mismatch is a risk factor for de novo DSA and AMR in kidney transplantation recipients. Furthermore, the number of HLA class II eplet mismatches has greater significance as a risk factor than the number of conventional HLA class II mismatches.