Clinical relevance of major histocompatibility complex class I chain–related molecule A (MICA) antibodies in live donor renal transplantation – Indian Experience

Abstract

Antibody-mediated rejections (AMR) in the absence of circulating anti-HLA-DSA have highlighted the role of non-HLA antibodies, particularly those directed against endothelial cells. Of these, MICA (major histocompatibility complex class I chain–related molecule A) antibodies are the most notable and important because of their potential in promoting graft rejections. Limited studies have focused on the impact of MICA donor-specific antibodies (DSA) on graft outcome as compared to those that are not donor-specific (NDSA). We evaluated pre- and post-transplant sera at POD 7, 30, 90, 180 and the time of biopsy from 206 consecutive primary live donor renal transplant recipients for anti-MICA and anti-HLA antibodies using single antigen bead assay on a Luminex platform. Recipients who developed MICA antibodies and their donors were phenotyped for MICA alleles. For the purpose of antibody analysis, patients were categorized into three major groups: biopsy-proven AMR, acute cellular rejection (ACR) and those with no rejection episodes (NRE). During the mean follow-up period of 17.37 ± 6.88 months, 16 of the 206 recipients developed AMR, while ACR was observed in only 13 cases. A quarter (25%) of the AMR cases had anti-MICA antibodies as compared to 7.7% of those experiencing ACR and 6.2% of the NRE group. Allelic typing revealed that all MICA Ab +ve AMR cases were due to the presence of donor-specific antibodies. MICA-DSA even in the absence of HLA-DSA was significantly associated with AMR but not with ACR when compared with the NRE group (P = <.01).