Update of the HLA class I eplet database in the website based registry of antibody-defined HLA epitopes.

Eplets are small configurations of polymorphic amino acid residues on human leukocyte antigen (HLA) molecules and are considered as essential components of HLA epitopes recognized by antibodies. This report describes a new design of the eplet repertoire in HLA-ABC alleles used in Luminex kits for antibody testing. There were three steps (1): identify all combinations of polymorphic residues with HLA molecular modeling within a 3-Å radius, (2) determine polymorphic residue compositions of 3 Å patches from amino acid sequences of HLA alleles in Luminex panels and (3) annotate eplets from one or more patches present on one allele or shared by the same group of alleles. There are now 270 HLA-ABC eplets in the Registry, of which 219 are in antibody-accessible positions on the molecular surface and 51 are defined solely by residue polymorphisms located below the molecular surface. Each eplet has a list of Luminex and non-Luminex alleles for which mismatch acceptability can be determined.