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

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 =