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.

ABO incompatible kidney transplantation --immunological aspect-.

ABO incompatible kidney transplantation (ABOINCKT) has been developed in Japan because of the shortage of cadaveric donors. We have performed 76 living-donor ABOINCKT in our center. Donor blood type antibody was removed by immunoadsorption or plasmapheresis and exchange. Immunosuppression consisted of cyclosporine or tacrolimus, steroid, and cyclophosphamide or azathioprine or mycophenolate mofetil and, recently, basiliximab. Splenectomy was routinely performed during the transplantation surgery. Donor blood type antigen was strongly expressed on the vascular endothelium at all time points and in all conditions posttransplantation. Red blood cell agglutination reaction (RBAR) was positive only in renal tissues from a patient with delayed hyperacute rejection. Donor specific antibody suppression was observed in 18 ABOINCKT recipients with blood type O from a donor with blood type A1 or B. ADCC activity was detected after pre-treatment. Acute humoral rejection in ABOINCKT can result from ADCC, as well as by antigen-antibody reaction. Five year graft and patient survival rates were 75% and 64% in 37 ABOINCKT recipients from June 1989 through December 1996, however they have been 100% in 39 ABOINCKT recipients since January 1997. Accommodation has been produced in ABOINCKT with the co-existence of blood type antigen and antibody. Currently, ABOINCKT is an alternative which should be considered, particularly for blood type O patients with extended waits for cadaveric transplantation and for pediatric patients.