Pretransplant donor-specific antibodies in cytotoxic negative crossmatch kidney transplants: are they relevant?

Background. The corresponding antigens of alloantibodies identified in patients awaiting kidney transplantation are often listed as unacceptable for transplantation. The use of solid phase testing, being more sensitive and accurate than conventional complement-dependent cytotoxicity (CDC) assays, has resulted in increased identification of alloantibodies. We aimed to study the clinical importance of alloantibodies defined solely by solid phase techniques. Methods. All patients transplanted between 1999 and 2001 at our center with available day-of-transplant sera (D0) were included (121 patients). All had negative CDC crossmatches. Results. Thirty-eight patients (31%) had detectable alloantibodies using high-definition assays with 16 having donorspecific antibodies (DSA) and 22 non-DSA. There were no cases of hyperacute rejection in any of the groups. Biopsyproven acute rejection rates in the DSA and non-DSA were similar to the unsensitized group. Delayed graft function and 1-year graft survival rates were also similar for the three groups as were median 1-year serum creatinine levels. Multivariate analysis, however, showed that DSA were associated with an increased relative risk of longer-term graft failure (relative risk, 6.5; P0.05). Conclusions. These data show that in the context of a CDC-negative crossmatch, the presence of D0 DSA has little impact on any early graft parameters. DSA, however, are associated with poorer longer-term graft outcomes in kidney transplantation.