BACKGROUNDIn addition to the well-known antibodies against human leukocyte antigens (HLA)-induced kidney-graft rejection, polymorphic major-histocompatibility-complex (MHC) class I-related chain A (MICA) antigens can elicit antibodies and have been suggested to play a role in the antibody-mediated allograft rejection (AMR). We carried out a prospective study of MICA antibodies in post-renal transplant patients to determine the association between MICA antibodies, C4d staining, histological features, and graft outcome.

METHODSWe tested 52 patients who had biopsy results due to graft dysfunction. The MICA antibodies in concurrent sera were determined by Luminex. All patients were followed up for one year after renal biopsy. The influence of antibody production on the function of graft was analyzed.

RESULTSAntibodies against MICA were positive in 15 out of the 52 patients (28.9%). The presence of MICA antibodies was associated with renal-allograft deterioration. During one-year follow-up, the estimated glomerular filtration rate (eGFR) decreased (24.0 ± 3.4)% among recipients with anti-MICA antibodies. However, among recipients without anti-MICA antibodies, the eGFR has declined only (8.4 ± 3.0)% (P = 0.017). The association between C4d staining, histological features and MICA antibody production was found no significant difference.

CONCLUSIONBesides anti-HLA antibodies, the presence of post-transplant MICA antibody is associated with poor graft outcome and increases the risk of graft failure.