Zou Y et al. (2007) Antibodies against MICA antigens and kidney-transplant rejection. N Engl J Med 357: 1293–1300

Antibodies against major histocompatibility complex (MHC) class I-related chain A (MICA) antigens might be involved in renal allograft rejection. MICA antigens are not expressed on peripheral blood lymphocytes, the cells that are usually used for crossmatching, but are expressed on endothelial cells, dendritic cells, epithelial cells and fibroblasts.

Zou et al. tested pretransplantation serum samples from 1,910 deceased-donor kidney transplant recipients for anti-MICA antibodies to determine whether the presence of these antibodies affected clinical outcome.

Anti-MICA antibodies were present in the pretransplantation serum samples of 217 (11.4%) kidney transplant recipients. The 1-year graft survival rate ± SD was significantly lower in patients with anti-MICA antibodies than in those without (88.3 ± 2.2% vs 93.0 ± 0.6%; P = 0.01). Among patients who had received a first transplant, this result was even more significant (graft survival rate 87.8 ± 2.4% in the 183 patients with anti-MICA antibodies vs 93.5 ± 0.6% in the 1,473 patients without anti-MICA antibodies; P = 0.005). The association between the presence of anti-MICA antibodies and reduced graft survival was particularly strong among the 326 patients who received kidneys that were well-matched in terms of human leukocyte antigen (HLA)-A, HLA-B and HLA-DR (graft survival 83.2 ± 5.8% among those with anti-MICA antibodies vs 95.1 ± 1.3% in those without anti-MICA antibodies; P = 0.002).

The authors conclude that MICA antibodies might contribute to graft loss in kidney transplant recipients who receive organs from donors that are well-matched for HLA. Screening for anti-MICA antibodies in patients awaiting kidney transplantation might be a useful method to identify those at risk for graft failure.