A Case of ABO-Incompatible Kidney Transplantation for a False-Positive T and B-Cell Crossmatch Test Due to Anti-A Antibodies.

The recipient was a 50-year-old man with blood type O who was referred to our department for a pre-emptive ABO-incompatible kidney transplantation (KTx), with his wife as the donor whose blood was type A. However, both of the T and B cell complement-dependent crossmatch and flow cytometric crossmatch tests showed positive results. Even though donor-specific antibodies were negative by Luminex, we did not recommend transplantation and he had received dialysis therapy for 3 years. We conducted a re-evaluation of crossmatch tests. IgM and anti-B antibody were eliminated from the recipient's sera by the processing with dithiothreitol and the absorption mixing type B red blood cells. However, crossmatch tests still showed positive. Then, we eliminated anti-A antibody by the absorption mixing type A red blood cells. T- and B-cell crossmatch tests turned to negative, suggesting anti-A antibody in the recipient's sera binds to type A substance onto the donor's T and B lymphocytes. The recipient received an ABO-incompatible KTx with our standard desensitization therapy. Immediate graft function was achieved without any rejection.