P075 Generation of an algorithm to standardize HLA typing information for UNOS

• Published in: Human immunology Vol. 77; p. 91
• Main Authors: Brown, Nicholas K, Upchurch, Rebecca L, Weidner, Jerome G, Marino, Susana R
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2016
• Subjects: Allergy and Immunology
• ISSN: 0198-8859; 1879-1166
• DOI: 10.1016/j.humimm.2016.07.140

Aim The United Network for Organ Sharing (UNOS), the sole contractor for deceased-donor transplantation in the US, requires HLA type in serologic nomenclature. Currently, however, the vast majority of patients and donors are typed by molecular methods. The 2008 HLA dictionary (hla.alleles.org/dictionary), which lists serologic assignments for many HLA-A, B, C, DRB1, DRB3/4/5 and DQB1 alleles, is used to “translate” molecular typing to serologic equivalents. However, many HLA alleles have multiple or conflicting entries in the HLA dictionary, while many rare or newly-identified alleles are not present. Moreover, UNOS accepts many “serologic” designations that do not appear in the HLA dictionary. To overcome these limitations, we created an algorithm to compile an internal document for UNOS-specific HLA type. Methods The 2008 HLA dictionary and Organ Procurement and Transplantation Network standards were used as primary sources for HLA typing information. Predicted amino acid sequence was used to assign Bw4/w6 (Tissue Antigens 2001: 57: 474). Results The algorithm, summarized below, was used to determine serologic assignments, which we termed “UNOS equivalents.” Expressed DRB3, DRB4 or DRB5 alleles were listed as DR52, DR53, or DR51, respectively, regardless of HLA dictionary assignments. Similarly, HLA-C alleles with first-field numbers greater than 08 were assigned UNOS equivalents corresponding to their first-field numbers, regardless of HLA dictionary assignments. For other alleles, the “Expert” assignment was given precedence over the “WHO” assignment listed in the HLA dictionary. Alleles not appearing in the HLA dictionary were assigned UNOS equivalents based on the first-field number. For alleles with multiple or conflicting entries, an algorithm was written to result in a single UNOS equivalent. For B∗15 alleles with unknown Bw4/w6 assignments, a published algorithm was used. Conclusions The algorithm described here resulted in a document that standardizes the “translation” of HLA alleles to list in UNOS, so that a single UNOS equivalent can be obtained from any HLA-A, B, C, DRB1, DRB3/4/5, or DQB1 type. As subsequent serologic studies are published, this document can serve as a framework for determining typings to enter into UNOS, to facilitate efficient sharing of deceased donor organs.