129-P

Abstract

Aim Considering the incidence of solid organ transplant recipients who are sensitized with DP antibodies, improved methods of DP typing and of antigen equivalent grouping would be useful. A lack of serological information about most DP molecular genotypes impedes ready assignment into “serological equivalents” as practiced with other HLA loci. Since DP antibodies are most commonly identified by Single Antigen Bead (SAB) tests, the current state of the art requires comparing complicated DP genotyping data with SAB results from only a limited set of beads. We therefore sought a new, rapid method of molecular DP typing with practical “serological equivalent” assignments. Methods Linkage Biosciences’ real-time PCR technology combining allele specific amplification with melt curve detection (LinkSēq™) was used in blinded testing against a set of previously typed samples with a broad range of DP specificities. Since DP antibody response is most often directed toward a limited number of immunodominant hypervariable region epitopes, we focused on the six critical epitope regions of exon 2 of the beta locus as well as the four major groups of the alpha locus to assign DP Epitypes. Results LinkSēq reduced test time by 50% and hands-on time by up to 90% compared to SSP or SSO methods, and all LinkSēq types were concordant with the expected types. 149 HLA-DP alleles (IMGT v3.5.0) were readily grouped into 103 Epitypes based on the pattern of epitopes in each DP allele. SureTyper™ software then used donor and recipient DP genotyping information, combined with recipient SAB results, to enable an automated virtual crossmatching tool. Conclusions LinkSēq offers a rapid method of DP genotyping with a simple workflow and avoidance of post-amplification contamination. SureTyper software provides a practical approach to Epityping DP alleles, determining Epitype compatibility, and allowing virtual crossmatching without tedious manual identification of cognate antibody-epitope pairings. Antovich: Linkage Biosciences: Employee; Stockholder. Russnak: Linkage Biosciences: Employee; Stockholder. King: Linkage Biosciences: Employee; Stockholder. Ly: Linkage Biosciences: Employee; Stockholder. Quinto: Linkage Biosciences: Employee. Grumet: Linkage Biosciences: Consultant; Stockholder.