LONG-TERM RESULTS OF ABO-INCOMPATIBLE LIVING KIDNEY TRANSPLANTATION

Abstract

Background. Despite great efforts to promote the donation of cadaveric organs, the number of organ transplantations in Japan is not increasing and a serious shortage of cadaveric organs exists. These circumstances have forced a widening of indications for kidney transplantation. For this purpose, ABO-incompatible living kidney transplantations (LKTs) have been performed. Although we have already reported the short-term results of ABO-incompatible LKT, there is no report of long-term results in such cases; anti-A and anti-B antibodies could cause antibody-induced chronic rejection and result in poor long-term graft survival. In this study, we have reviewed the long-term results of ABO-incompatible LKT and tried to identify the most important factors for long-term renal function in ABO-incompatible LKT. Methods. Sixty-seven patients with end-stage renal failure underwent ABO-incompatible living kidney transplantation at our institute between January, 1989, and December, 1995. The mean age was 34.9 years (range, 8-58 years), with 38 males and 29 females. Incompatibility in ABO blood group antigens was as follows: A1→O, 23 patients; B→O, 19 patients; A1B→A1, 7 patients; B→A1, 8 patients; A1→B; 4 patients; A1B→B, 4 patients; A1B→O, 2 patients. The number of HLA-AB, and -DR mismatches were 1.6±1.1 and 0.76±0.6, respectively. Plasmapheresis and immunoadsorption were carried out to remove the anti-AB antibodies before the kidney transplantation. In the induction phase, methylprednisolone, cyclosporine, azathioprine, antilymphocyte globulin, and deoxyspergualin were used for immunosuppression. Local irradiation of the graft was performed at a dose of 150 rad, on the first, third, and fifth days after transplantation. Splenectomy was done at the time of kidney transplantation in all cases. Results. Patient survival was 93% at 1 year and 91% at 8 years. Graft survival was 79% at 1, 2, 3, and 4 years, 75% at 5 and 6 years, and 73% at 7 and 8 years. Patient survival was not significantly different from that of ABO-compatible patients. However, graft survival was significantly different between ABO-incompatible grafts and ABO-compatible grafts. Specifically, ABO-incompatible transplant recipients experienced a significantly higher rate of early graft loss up to 3 years but showed an equivalent graft loss by year 4. Among 67 patients, 16 grafts were lost during the observation period. Loss was due to acute rejection in 5 patients, followed by chronic rejection in 5 patients and death with function in 3 patients, whereas immunosuppression was withdrawn in 3 patients due to nonimmunological reasons. Of 16 grafts lost, 15 were lost within 1 year after transplantation. Of the 67 patients, 5 died during observation. Three patients with functioning grafts died of uncontrolled bleeding due to duodenal ulcer, malignant lymphoma, and cerebral hemorrhage (one patient each). One patient died of ischemic colitis due to secondary amyloidosis and one patient of cerebral hemorrhage after graft loss due to humoral rejection. There was no fatal infectious complication, whereas 10 patients had non-tissue-invasive cytomegalovirus infection. The stepwise logistic regression model was employed to identify the most important factors for long-term renal function. Patients were subdivided into those with serum creatinine of less than 2.0 mg/dl (group 1, n=39) versus those with serum creatinine of more than 2.0 mg/dl (group 2, n=22) at one year after renal transplantation. Six patients were excluded because of death with functioning graft (three patients) and withdrawl of immunosuppression (three patients). Rejection episodes within 6 months were significantly frequent in group 2 compared with group 1 (P=0.0008). Odds ratio was 112-fold in the rejection episodes. Obviously, the high incidence of early humoral rejection is caused by ABO incompatibility, because ABO-incompatible grafts experience a higher rate of early rejection and graft loss compared with ABO-compatible grafts. This means that ABO incompatibility is, principally, the most important factor to affect graft function in ABO-incompatible LKT. Donors who were over 54 years old were also significantly frequent in group 2 compared with group 1, and the odds ratio was 12 in the donors who were over 54 years old. HLA-DR mismatches and pre-operative maximum anti-AB IgG showed a significant difference between group 1 and group 2. However, these differences were much less than those of donor age and rejection episodes. There were no significant differences between group 1 and group 2 in terms of recipient age, HLA-AB mismatches, anti-AB IgM antibody titers, incompatibility of blood type, and sex. Conclusions. ABO-incompatible living kidney transplantation offers an excellent long-term outcome and is an acceptable treatment for end-stage renal failure. Long-term renal function in ABO-incompatible LKT is primarily influenced by the occurrence of acute rejection episodes within 6 months, associated with ABO incompatibility and a higher donor age (over 54 years old).