Donor-specific HLA class I and CREG antibodies in complement-dependent cytotoxicity-negative renal transplants

Development of a solid-phase, single antigen panel reactive antibody test (SA-PRA) permits the analysis of antibody specificities. This study determined the impact of donor-specific antibodies (DSA) against class I HLA private antigens (DS-HLA) or HLA-A and -B cross-reactive group (DS-CREG) in kidney transplantation. Pre- and post-transplant sera of 133 renal allograft patients who had negative pretransplant complement-dependent cytotoxicity were tested for HLA class I antibody specificities by SAPRA. Clinical relevance of the flow cytometric crossmatch test (FCXM) for the detection of class I DSHLA or DS-CREG was analyzed. The sensitivity of FCXM to detect SA-PRA-defined class I DSA was 50% (5/10) and the specificity was 98.4% (121/123). Of 133 renal allograft recipients, including 26 patients with biopsy-proven acute antibody-mediated rejection (AMR), pretransplant DS-HLA or DS-CREG were detected in 10 patients. Pretransplant DSA were associated with AMR (p = 0.012) and a low calculated glomerular filtration rate (p = 0.036). In the analysis of post-transplant sera, the presence of either type of HLA antibodies and the de novo development of DSA were correlated with AMR (p <0.001). This study demonstrates that detection of DSA, including DS-HLA and DS-CREG, using the SA-PRA assay is useful to identify the renal allograft recipients with poor transplant outcome.