Are you aware of MICA antibodies?

Some kidney transplants fail despite good HLA matches. The main targets for antibody mediated rejection are HLA antigens. Among non-HLA antigens that can induce an antibody response, MHC class 1-related chain A (MICA) antigens appear significant enough to affect acute and chronic graft outcomes. MICA antigens are expressed on endothelial cells, dendritic cells, fibroblasts, epithelial cells but not on peripheral blood lymphocytes. As they are expressed on endothelial cells, it seems that antibodies against MICA antigens are harmful especially to vascularized allografts like renal allograft. In a landmark study (Zou et al, NEJM Sep 2007), pretransplantation MICA antibodies were found in about 11% of 1910 renal transplant recipients. It was found that recipients with pre-transplantation MICA antibodes had lower 1-year graft survival compared to those without MICA antibodies suggesting adverse role of these antibodies. However, a more recent but smaller study (Lemy et al, Transplantation, May 2010) failed to replicate same findings. In this study, MICA antibodies did not adverse affect renal allograft outcomes.