The clinical significance of conversion of complement-dependent cytotoxic T cell crossmatch test after renal transplantation.

The purpose of this study was to investigate the clinical relevance of conversion of post-transplant T cell crossmatch between kidney donor and recipient. This study comprises 892 cadaveric renal transplantations performed on 874 adult patients between August 1991 and December 1997. Recipient selection was based on a negative complement-dependent cytotoxic T cell crossmatch test with current (< or = 2 months old) serum. For this study, on day 0 and day 14 after transplantation, serum samples were collected for later crossmatching. On day 14 after transplantation, the crossmatch had converted to positive in 76 transplantations (8.5%). Acute rejection occurred in 50% of the converters and 22% of the non-converters (P < 0.005), and graft survival was significantly poorer (P < 0.025), being 85 vs 94% at 1 and 68 vs 83% at 5 years, respectively. In patients with delayed graft function, 1-year graft survival was 77% in the converters and 91% in the non-converters (P < 0.05). Conversion of T cell crossmatch, especially in connection with delayed graft function, identifies a subgroup of patients at high risk of severe rejection and poor graft survival.