Chronic humoral rejection mediated by anti-HLA-DP alloantibodies: insights into the role of epitope sharing in donor-specific and non-donor specific alloantibodies generation.

We report the case of a renal transplanted patient, in whom the detection of a unique anti HLA-DP antibody response preceded the development of chronic humoral rejection. In addition to donor-specific anti-DP alloantibodies, the patient displayed reactions against several non-donor-specific DP antigens (NDSA). Interestingly, we found that all the DP molecules recognized by the alloantibodies displayed the same amino-acid sequence suggesting that epitope sharing between unrelated HLA molecules was the mechanism underlying NDSA generation. This case highlights the pathogenicity of anti-DP alloantibodies and suggests that it could be more meaningful to match the epitopes than the HLA antigens for the prevention of rejection.