Detection of allogeneic blood group A and B enzyme activities in patients with ABO incompatible kidney transplantation.

The phenomenon of accommodation in recipients of blood group ABO incompatible kidney transplantation (iKTx), in which grafts survive despite the presence of blood group A or B antigen in the graft and the presence of corresponding antibodies in the recipient's blood, is not uncommon. alpha1,3-N-Acetylgalactosaminyltransferase and alpha1,3galactosyltransferase associated with the synthesis of blood group A and B antigen (A and B enzymes), respectively, were measured by a highly specific enzyme-linked immunosorbent assay in the sera and transplanted tissues of patients who underwent an ABO iKTx. Allogeneic A and B enzymes were present in the sera and tissues as well as A and B antigens in the tissues for a long period, which hitherto have never been seen in recipients prior to an iKTx. However, activities of these enzymes in the sera after an iKTx decreased in patients who experienced a serious acute antibody-mediated rejection and disappeared in patients who had an unrepairable rejection, leading to graft loss without establishment of accommodation. Our observations on the presence of allogeneic A and B enzymes in the recipients' sera should have implications in decision making for a successful iKTx.