Association Between <scp>HLA</scp> ‐ <scp>DRB1</scp> Serotype and <scp>HLA</scp> ‐ <scp>DQB1</scp> Allele Mismatches and Acute Rejection in Kidney Transplantation

The purpose of this single-center case-control study was to investigate the association between HLA serotype mismatch (MM), compared to other HLA MM modalities, and the occurrence of acute rejection (AR) within the first year after deceased donor kidney transplantation. The study included 198 transplants in 99 pairs of recipients of kidneys from the same donor, where one recipient experienced AR and the other survived the first year without AR. Donors and recipients were typed with NGS for 11 HLA loci at high resolution. HLA MM categories included allele groups, alleles, serotypes, amino acids, EMMA, eplet and PIRCHE-II. Additionally, we investigated Cytomegalovirus LIL peptide (CMV LIL) MM. Recipients with AR presented higher frequencies of pre-transplant HLA-ABDR DSA (20.2% vs. 6.1%, p = 0.005) and CMV LIL MM (24.2% vs. 10.1%, p = 0.01). Univariate and multivariate Cox proportional hazards regression for matched-pair analyses were used to test the association between HLA MM and AR. Univariate analyses indicated significant association with DRB1 ST, HLA-DQB1 AG, HLA-DQB1 AL, EMMA C, EMMA DQB1, Eplet ABC and Eplet DQ MM. Different models were tested in multivariate analyses, all including pre-transplant HLA-ABDR DSA and CMV LIL MM. The models were compared using the Akaike Information Criterion (AIC). The best estimate for AR prediction (AIC = 97.6) was the model that included pre-transplant HLA-ABDR DSA (HR = 11.97; p = 0.003), CMV LIL MM (HR = 367.2; p < 0.001), HLA-DRB1 serotype MM (9.65; p = 0.002) and HLA-DQB1 allele MM (HR = 3.54; p = 0.033). In conclusion, this original report demonstrates an association between the HLA-DRB1 serotype MM and AR, highlighting that serotypes are clinically relevant.