359: Virtual crossmatch improves organ allocation in sensitized patients

Abstract

Purpose: Heart transplantation (tx) in patients with human leukocyte antigen (HLA) sensitization presents challenges in organ allocation. A requirement of a conventional prospective crossmatch effectively halts the use of distant donors (DD) in these patients, resulting in longer wait times. The use of ‘virtual crossmatch’, in which the sensitized recipients’ HLA antibody profiles are determined by Class I and II LabScreen® PRA beads on a Luminex platform and compared to the antigen profile of the donor, could increase the use of allografts from DD. Methods and Materials: All sensitized recipients tx since 2001 in whom antibodies to specific Class I and II HLA antigens were identified were included in the analysis. For these patients, conventional prospective crossmatch was required when allografts were procured from local donors (LD), while virtual crossmatch was required when allografts were procured from DD. Results: Thirty-one patients met the inclusion criteria. Fifteen patients received allografts from LD with negative conventional prospective crossmatch. Sixteen patients (52%) were transplanted with allografts from DD with negative virtual crossmatch. Detailed clinical outcomes data are listed in Table 1. Of note, three of the DD patients had a positive retrospective crossmatch, were treated with plasmapheresis and all three are alive. Conclusions: Virtual crossmatch by HLA typing allowed utilization of allografts from DD in more than half of sensitized patients. While antibody-mediated rejection was more common with tx from DD, intermediate-term mortality was not unfavorably affected. Virtual crossmatch in heart tx is likely to improve organ allocation in sensitized patients.