Different eplet software programs give discordant and incorrect results: An analysis of HLAMatchmaker vs Fusion Matchmaker Eplet calling software

HLA eplet matching is a novel approach to define acceptable HLA mismatches for transplant recipients. We performed an eplet analysis of three different transplant case-series to determine if the available software programs gave accurate results. Eplet analysis was performed for three different transplant case-series typed by NGS for all HLA class I and II loci. The three different HLA datasets were entered into both the HLAMatchmaker program (v2.1) and OLI Fusion MatchMaker (v4.2) software tools. Eplet results which were discordant were cross referenced against eplet registry and published HLA allele sequence data to determine the correct assignments. The comparison reveals that there was poor concordance between the two eplet programs. Analysis of the same donor/recipient pair often gave rise to different total eplet scores, incorrect eplet mismatches and antibody verification status, and both programs have eplets assigned to incorrect HLA alleles. Overall, the OLI Fusion MatchMaker eplet tool gave more accurate and useful eplet results. Eplet matching is still primarily a research tool. Before eplet matching can enter routine clinical practice further work is required to validate the accuracy of available eplet software programs. Incorrect eplet assignment could have serious adverse consequences in the clinical transplant setting.

Towards uniformity in the definition of acceptable mismatches for highly sensitized patients

The Eurotransplant (The Eurotransplant International Foundation) acceptable mismatch programme has been shown to be a successful tool to enhance transplantation of highly sensitized patients(HSPs). However, patients with rare HLA phenotypes in relation to the Eurotransplant donor population remain on the waiting list. EUROSTAM is an European Union funded project to explore the feasibility of a Europe‐wide acceptable mismatch programme enabling transplantation of HSPs with rare HLA phenotypes within their own organ exchange organization. The present study, which forms part of the EUROSTAM project, assesses the differences in the practices of the laboratories in different countries with respect to their HLA antibody profiling and risk adverseness. In the serum exchange exercises of 18 samples, a high level of variability has been shown in both assays and interpretation of results. In the data exchange exercise when all participants were given the same Luminex raw data for analysis, a high degree of consensus was reached where the median fluorescent intensity values of beads were <500 and >2000 for standard single antigen bead assays, or <500 and >5000 for assignment of acceptable mismatches. The risk adverseness analysis has showed distinct patterns of attitudes towards the perceived risks based on HLA antibody assay results, most probably influenced by the local protocols of the clinical transplant programme of each laboratory. In order to ensure fairness and maintain consistencies of organ exchange among partner transplant centres, a centralized facility will be instrumental for a uniform definition of acceptable mismatches.

Transplantation in highly sensitized patients: challenges and recommendations

INTRODUCTION

Highly sensitized patients awaiting a kidney transplant accrue on the transplant waiting list. The breadth of HLA antibodies in this subpopulation of patients precludes receiving a compatible organ offer through regular allocation within an acceptable time-frame. Areas covered: Several alternative options to receive a transplant exist for these patients, including additional priority in regular allocation, special programs based on allocation through acceptable antigens, kidney paired donation programs, desensitization protocols, or a combination of the latter two. In this review, these options and their outcomes are discussed as well as some possibilities to further enhance transplantation of this disadvantaged group of patients. Expert commentary: For highly sensitized patients, special attention is required, for which several strategies may apply. A step-wise approach may be the optimal strategy to facilitate successful transplantation of highly sensitized patients.