Accelerated acute rejection of an apparent A2 renal allograft in an O recipient: report of a case with flow cytometric analysis.

We report a case of accelerated acute rejection of a renal allograft from a presumed ABO histo-blood group A2 donor in an O recipient, in which all of the published criteria for compatibility had been met. Flow cytometric analysis of the A and H antigen expression on the kidney donor's erythrocytes suggested that this donor did not have an A2 phenotype, but rather another subgroup of A. Some of the reported cases of accelerated acute rejection of A2 renal allografts in O recipients may have resulted from misapplication of the results of standard lectin agglutination to the transplant setting. The current case suggests that a more sophisticated method of ABO phenotyping, such as erythrocyte flow cytometric analysis, may be necessary in the transplant setting.