SERIAL TEN YEAR FOLLOW-UP OF HLA AND MICA ANTIBODY PRODUCTION BEFORE KIDNEY GRAFT FAILURE

Abstract

P10 Aims: The role of HLA and MICA antibodies in chronic allograft rejection is difficult to establish since many patients who have antibodies have good kidney function. Since it takes many years for antibodies to ultimately cause chronic rejection, we utilized a unique sera resource over a 10-year period on patients who either rejected or retained their grafts. Methods: We retrospectively examined serum samples from 43 patients who rejected their grafts which had functioned for over 1,000 days. Sera from 30 functioning patients were examined as controls. Patients who died or had recurrent disease were excluded. Samples were taken at roughly 6 month intervals and a total of 718 samples (rejected:397, functioning:321) were tested against HLA Class I, HLA Class II with LABScreen PRA Class I & II beads and recombinant lines of MICA 1,2,4,7,8,12,17,and 18. Since multiple samples from one patient were tested, it was possible to determine the consistency of antibody detection on consecutive serum sample dates. Results: HLA antibodies were found in a significantly higher incidence among patients who rejected grafts (53%) than patients with functioning transplants (30%) (p<0.05). Among patients who had no HLA antibodies, again, the incidence of MICA antibodies was significantly higher among patients who eventually failed (55%), compared to those who still had functioning transplants (24%) (p<0.05). Overall, the incidence of HLA and MICA antibodies was higher (79%) among those whose transplants failed than those whose transplants were functioning (47%) (p<0.01). Conclusions: These results indicate that among patients who eventually rejected their grafts, HLA and MICA antibodies were more frequently present than among those who had functioning grafts, suggesting that these antibodies were responsible for the failures.Figure