Heart transplantation with donor-specific antibodies directed toward denatured HLA-A*02:01: a case report

The development of solid-phase assays for antibody detection has aided in the frequent detection of human leukocyte antigen (HLA) antibodies in nonalloimmunized males. Some scientists have reported that these HLA antibodies are produced to pathogens or allergens and the reactivity with HLA coated beads is the result of cross-reactive epitopes. These antibodies may also be directed toward cryptic epitopes exposed on the denatured beads. In this report, we describe the case of a heart transplanted patient who exhibited anti-HLA-A*02:01 donor-specific antibodies detected with a bead-based assay (Luminex) and undetected with the complement-dependent cytotoxicity (CDC) test. Posttransplant monitoring, carried out with CDC and with Luminex on sera from this patient collected at the 2nd, 4th, 8th, and 12th posttransplant weeks and at 1 year confirmed the presence of anti-HLA-A*02:01 in all serum samples. Additional tests carried out with denatured and intact HLA molecules using single antigen beads demonstrated that the antibody was directed toward a cryptic epitope. One year after transplantation the patient is doing well. No sign of antibody-mediated rejection was observed throughout the follow-up. A comprehensive evaluation of the anamnesis and of antibodies is critical to avoid needless exclusion of organ donors.