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.