Clinical outcome and accommodation in ABO incompatible kidney transplantation.

We performed 84 ABO-incompatible kidney transplants at Toho University since 1989, with plasmapheresis and exchange replacing AB blood group plasma as pre-conditioning to reduce anti-donor blood group antibodies. Our current immunosuppression protocol consists of basiliximab, MMF, steroid, and cyclosporine or tacrolimus, including splenectomy. Overall patient/ graft survival rates (n=84) were 95/93 at one year, 94/92 at 3 years, 87/80 at 5 years, 87/75 at 7 years, and 83/67 at 10 years. The outcomes are similar to those of ABO-compatible living donor transplants. We have achieved 100% graft and patient survival rates (n=48) for the 7 years since January 1997. Our findings suggest that post-conditioning is not necessary to control titers of anti-donor blood group antibodies or to overcome acute humoral rejection. Infection control is critical in achieving good outcomes in ABO-incompatible transplants. We found that only anti-donor blood group antibodies in blood group O recipients of ABO-incompatible kidneys were specifically suppressed one year after transplantation. This appeared to be a type of accommodation in which there was no immunological response despite the co-existence of donor antigen and antibody, and might have been caused by down-regulation of B cells to produce anti-donor antibody.