12-P

Abstract

HLA laboratories are required to perform antibody analysis using a solid phase assay, and to report unacceptable antigens to UNOS in order for recipients to receive the point credit on the waitlist. Commonly a threshold is established above which an antigen is to be avoided. Yet the clinical relevance of even some highly reactive antibodies is doubtful. We report here a case of a 28yo cardiac transplant candidate with no history of HLA immunizing event whose Class II cPRA is 47% rendering him essentially untransplantable. HLA antibodies testing is by Luminex single antigen (SAB) and ID beads using reagents from both GenProbe (GP) and One Lambda (OLI). Crossmatching was performed by 3-color flow cytometry (FCXM). Patient presented for evaluation with non-ischemic cardiomyopathy in 2010. He had never received blood products. Initial HLA Ab screening by GP ID demonstrated DR1 9 and DR51 (single epitope 189R) confirmed by GP SAB with MFI 5-8000. An assist device (VAD) was placed 8/2011 and Ab testing performed 11/2011 yielded same specificities and increase in MFI to >13000. B cell FCXM with 14 random donors was performed. Eleven BFCXM were negative (including 3 DR1+ and 2 DR51+). Three BFCXM were weak positive with no HLA specific antigen. Testing using OLI SAB confirmed the specificities, but all were negative for Class II C1q. The antibody continues to be detected even under DTT or heat treatment. It is crucial that HLA specificities be verified using patient history and appropriate testing before being considered unacceptable to ensure opportunity for a life saving organ. In this case, with no correlative history, negative flow crossmatching and negative C1q, there is no evidence that the relatively strong specificities observed using 2 different vendor kits are detrimental to transplant. This patient is currently waiting for a heart transplant with no UA listed.