Evaluation of blood group antibodies in ABO-incompatible living-donor kidney transplantation.

OBJECTIVE: To assess changes in anti-blood type antibody titers and postoperative outcomes (graft survival and rejection rates) at our center with the use of the immunosuppressant, rituximab, in ABO-incompatible kidney transplants from living donors. Confirming anti-donor blood group antibodies is important for avoiding humoral rejection in ABO-incompatible kidney transplants. Splenectomy has been carried out in our hospital according to Alexandre's policy in order to suppress the production of anti-donor blood group antibodies. However, splenectomy has recently been avoided due to the administration of the immunosuppressant rituximab, which gives satisfactory outcomes. Thus, pre- and postoperative anti-donor blood group antibodies were measured, and the outcomes achieved with rituximab were examined.

METHODS: A total of 134 cases of ABO-incompatible kidney transplants were carried out at Toho University Omori Medical Center between March 1989 and February 2013. These cases were classified as follows: azathioprine group (n = 62 patients); mycophenolate mofetil group (n = 33 patients); rituximab group (n = 39 patients). The anti-donor blood group antibodies levels (immunoglobulin G and immunoglobulin M) were measured in all groups before antibody removal, immediately before surgery, and 1, 2, 4 weeks and 3 months after surgery, and then compared.

RESULTS: Rates of antibody-mediated rejection, including hyperacute rejection, in the azathioprine, mycophenolate mofetil, and rituximab groups were 32.2%, 18.1% and 7.6%, respectively. Graft survival rates were higher in the mycophenolate mofetil and rituximab groups than in the azathioprine group, but were lower in patients with higher preoperative antibody titers (≥128-fold higher immunoglobulin G) than in those with lower titers (<128-fold higher immunoglobulin G). In addition, postoperative anti-blood type antibody titers were significantly suppressed in the rituximab group.

CONCLUSIONS: Administration of rituximab results in better antibody control than previous protocols including splenectomy, even in the postoperative period during which humoral rejection often occurs. This protocol eliminates the physical invasiveness of pre-transplant splenectomy, and is expected to provide better outcomes in chronic renal failure patients who undergo kidney transplants.