ROLE OF ANTI-A/B ANTIBODY TITERS IN RESULTS OF ABO-INCOMPATIBLE KIDNEY TRANSPLANTATION1

Background Our previous studies showed that the incidence of humoral rejection was extremely high in ABO-incompatible living kidney transplantation. This result suggests that anti-A/B antibody titers directly influence the graft survival of ABO-incompatible kidney transplantation. In this study, we examined the impact of preoperative anti-A/B antibody titers on the results of ABO-incompatible living kidney transplantation. Methods Sixty-seven patients underwent ABO-incompatible living kidney transplantation at our institution between January 1989 and December 1995. The mean age was 34.9 years with 38 males and 29 females. Sixty-one of the 67 recipients were included in an analysis of the impact of anti-A/B antibody titer in long-term graft survival. The remaining six patients were excluded because of death with a functioning graft (three patients) and withdrawal of immunosuppression due to nonimmunological reasons (three patients) within 1 year after renal transplantation. Results The graft survival rate for the level of less than 1:16 in maximum IgG antibody before transplantation (n=21) at 1, 5, and 8 years was 81.0, 66.8, and 66.8%, respectively. The corresponding values for the level of 1:32-1:64 (n=33) and higher than 1:128 (n=7) were 93.9, 90.5, and 79.7%, and 42.9, 28.6, and 28.6%, respectively (log-rank test, P=0.0007). There was no significant association between maximum anti-A/B IgM titers, minimum anti-A/B IgM titers, minimum anti-A/B IgG titers, and graft survival. Conclusions Preoperative maximum anti-A/B IgG titers correlated with the long-term graft survival in ABO-incompatible living kidney transplantation. Thus, preoperative maximum levels of anti-A/B IgG titers are one of the good predictors of the results of ABO-incompatible living kidney transplantation.