RESUMO
BACKGROUND: The impact of major histocompatibility class I chain-related A (MICA) antibodies on renal graft outcomes is unclear. The goal of this work was to assess the impact of posttransplant MICA antibodies, assayed at 1 year, with two commercially available kits, on long-term renal graft outcomes. METHODS: We retrospectively tested sera from 779 kidney transplant recipients with two single-antigen flow bead assays 1 year after transplantation. Samples were considered positive for MICA if they were positive in both tests or positive for MICA specificities that were present in one kit only. The main outcome was 4-year death-censored graft survival. RESULTS: The prevalence of MICA antibodies was 5.4% at 1 year. MICA+ patients were more frequently human leukocyte antigen (HLA) sensitized and regrafted. Four-year death-censored graft survival was not different between MICA+ and MICA- patients (97% vs. 94%, P=0.28). By Cox multivariate analysis, independent risk factors for graft loss were as follows: number of HLA DR mismatches, acute rejection within the first year posttransplantation, 1-year serum creatinine, and the presence of HLA antibodies at 1 year, but not the presence of MICA antibodies. CONCLUSIONS: These data do not support an independent pathogenic role for MICA in long-term renal graft injury and question the interest of posttransplant monitoring of MICA antibodies with single-antigen flow bead assays currently available.
