Analysis of HLA class I specific antibodies in patients with failed allografts

Background. The goals of this study are first to determine the epitope specificity of donor specific antibody (DSA) in the serum of alloimmunized transplant patients with a failed renal graft; and second to understand the correlation between the development of DSA and nondonor specific antibody (NDSA). Methods. The sera of 35 pretransplant panel reactive antibody (PRA)-negative patients with failed allografts were examined with single-antigen (SA) luminex beads to identify human leukocyte antigen (HLA)-A and -B antibodies. Potential HLA antibody epitopes were identified by using computer software and verified by absorption and elution from single-antigen cell lines. Results. Twenty-seven patients developed donor-specific HLA-A and/or -B antibodies, while the remaining eight patients had only nonclonor-specific HLA-A and/or -B antibodies. The DSA-positive patients also had a long list of NDSA. Sixty-eight percent of the reactions found in 27 recipients with DSA were attributable to 66 epitopes on the mismatched donor HLA molecule. All 39 NDSA in eight patients with only NDSA shared 17 epitopes within positive allele specificities. By absorption and elution using recombinant cell lines having a single HLA specificity, we confirmed the epitopes involved in three patients. Conclusion. Development of most NDSA in patients with failed allografts is likely due to sharing epitopes with DSA and/or other NDSA.