OBJECTIVETo evaluate the association of major histocompatibility complex class I chain related gene A (MICA) antibodies with acute rejection (AR), chronic rejection (CR) and renal function after renal transplantation.

METHODSSerum MICA antibodies were detected with ELISA before and after transplantation with also examinations of panel reactive antibodies (PRA), serum creatinine, urine, graft ultrasound, lymphocyte subsets and the pathology of graft biopsy. The study was carried out in two parts to monitor MICA antibodies in acute and chronic rejections after renal transplantation.

RESULTSIn the first part of the study 18 of the 41 recipients experienced episodes of acute rejection, and the incidence rate was markedly higher in MICA(+) group than in MICA(-) group (P<0.05). Compared with the recipients with stable renal functions, the patients with acute graft rejection showed a significantly higher positivity rate of MICA antibodies. Postoperative MICA antibody monitoring showed that MICA antibody level increased gradually 2-3 days after the occurrence of acute rejection; anti-rejection treatment lowered serum creatinine to a normal level but MICA antibodies remained positive. In the second part, 21 of 40 patients had chronic graft rejection and showed significantly higher positivity rate of MICA than the patients with stable renal functions (P<0.05). In patients with chronic rejections, the serum creatinine levels were significantly higher in MICA(+) than in MICA(-) cases (P<0.05). Graft biopsy of all MICA(+) cases showed C4d deposition.

CONCLUSIONThe status of MICA antibodies can predict the occurrence and treatment outcomes of acute rejection, and also as one of the major causes of chronic graft rejection, they affect the long-term survival of the renal grafts.