14-OR

Abstract

To determine the incidence and clinical significance of donor specific antibodies (DSA) in renal allograft recipients with functioning grafts after more than 10 years post-transplantation. HLA antibody screening and identification were performed using One Lambda Single Antigen Bead (SAB) assay. Antibody capacity to fix complement was tested using the C1q assay (One Lambda). Serum samples were obtained from 182 recipients (mean age 43, female 35%, re-transplants 10%, live donor transplants 52%) with functioning grafts after more than 10 years post-transplantation (median time from transplantation 14 yrs, range 10-32 years). All recipients had a negative CDC crossmatch at the time of transplantation. After >10 years post-transplantation, 47% of the patients showed no evidence of sensitization to HLA antigens (cPRA ⩽ 10%, Ab-), 26% displayed cPRA > 10% in the absence of DSA (Ab+DSA-), and 25% displayed cPRA > 10% with DSA (Ab+DSA+). DSA directed to HLA class I, class II or both were identified in 9%, 14% and 2% of patients, respectively. The antibodies most frequently observed were directed to donor DQ antigens (8% of patients). To determine whether DSA had the capacity to bind complement, DSA+ sera were tested using the C1q assay. C1q binding DSA were observed in 47% of the DSA containing sera. Current serum creatinine levels were significantly higher in the Ab+DSA+ group compared to Ab- or Ab+DSA- group. However, there was no difference between creatinine levels in patients with C1q versus non-C1q binding DSA [ Table 1 ]. These results indicate that there is a close correlation between DSA detected late post-transplantation and graft function. Thus, DSA monitoring may assist in the long term management of renal transplant recipients and identifies patients with DSA who should not be considered for reduction in immunosuppression.