16th IHIW: A Website for Antibody‐Defined HLA Epitope Registry

<jats:title>Summary</jats:title><jats:p>The concept that <jats:styled-content style="fixed-case">HLA</jats:styled-content> antibodies are specific for epitopes rather than <jats:styled-content style="fixed-case">HLA</jats:styled-content> antigens is important not only for the determination of mismatch acceptability for sensitized patients but also for a better understanding of the antibody response to an <jats:styled-content style="fixed-case">HLA</jats:styled-content> mismatch. Numerous publications describe epitope‐specific antibodies, but there is no standardized information about the repertoire of clinically relevant <jats:styled-content style="fixed-case">HLA</jats:styled-content> epitopes. Under auspices of the 16th <jats:styled-content style="fixed-case">IHIW</jats:styled-content>, we have developed a website‐based registry of antibody‐verified <jats:styled-content style="fixed-case">HLA</jats:styled-content> epitopes. Epitope notations are based on <jats:styled-content style="fixed-case">HLA</jats:styled-content> molecular modelling of amino acid residues in polymorphic sequence positions. Informative epitope‐specific antibodies had been induced by a transplant, transfusion or pregnancy and were monoclonal antibodies or eluates of sera absorbed with single <jats:styled-content style="fixed-case">HLA</jats:styled-content> alleles. Antibody reactivity was determined in binding assays with single‐allele panels. Antibody producer/immunizer <jats:styled-content style="fixed-case">HLA</jats:styled-content> types enhanced the characterization of specific epitopes. The Registry also includes epitopes described in original research publications. Based on the extent of antibody reactivity information, we assigned epitope status as confirmed (well documented) or provisional (more data are needed). At present, the <jats:styled-content style="fixed-case">R</jats:styled-content>egistry has 69 <jats:styled-content style="fixed-case">HLA</jats:styled-content>‐<jats:styled-content style="fixed-case">ABC</jats:styled-content>, 53 <jats:styled-content style="fixed-case">DRB</jats:styled-content>1/3/4/5, 17 <jats:styled-content style="fixed-case">DQ</jats:styled-content>, 8 <jats:styled-content style="fixed-case">DP</jats:styled-content> and 22 <jats:styled-content style="fixed-case">MICA</jats:styled-content> antibody‐verified epitopes and will be updated on a quarterly basis. Laboratories worldwide continue to submit data about previously unreported antibody‐specific epitopes. For each epitope, the website shows its amino acid composition and <jats:styled-content style="fixed-case">HLA</jats:styled-content> alleles that share the epitope. Links show antibody reactivity patterns, sensitization information and references. Other links show molecular modelling of corresponding structural epitopes and polymorphic residue information for epitope‐carrying alleles. The website will also have a link to epitope frequency information in different populations. Search functions will list mismatched epitopes on mismatched alleles for selected <jats:styled-content style="fixed-case">HLA</jats:styled-content> types. The <jats:styled-content style="fixed-case">HLA</jats:styled-content> Epitope Registry will become a valuable resource for researchers interested in <jats:styled-content style="fixed-case">HLA</jats:styled-content> compatibility at the epitope level and investigating antibody responses to <jats:styled-content style="fixed-case">HLA</jats:styled-content> mismatches.</jats:p>