title: High T cell epitope sharing between two HLA-B27 subtypes (B*2705 and B*2709) differentially associated to ankylosing spondylitis.
abstract: HLA-B*2705 is strongly associated with ankylosing spondylitis (AS) and reactive arthritis. In contrast, B*2709 has been reported to be more weakly or not associated to AS. These two molecules differ by a single amino acid change: aspartic acid in B*2705 or histidine in B*2709 at position 116. In this study, we analyzed the degree of T cell epitope sharing between the two subtypes. Ten allospecific T cell clones raised against B*2705, 10 clones raised against B*2703 but cross-reactive with B*2705, and 10 clones raised against B*2709 were examined for their capacity to lyse B*2705 and B*2709 target cells. The anti-B*2705 and anti-B*2703 CTL were peptide dependent as demonstrated by their failure to lyse TAP-deficient B*2705-T2 transfectant cells. Eight of the anti-B*2705 and five of the anti-B*2703 CTL clones lysed B*2709 targets. The degree of cross-reaction between B*2705 and B*2709 was donor dependent. In addition, the effect of the B*2709 mutation (D116H) on allorecognition was smaller than the effect of the other naturally occurring subtype change at this position, D116Y. These results demonstrate that B*2705 and B*2709 are the antigenically closest HLA-B27 subtypes. Because allospecific T cell recognition is peptide dependent, our results imply that the B*2705- and B*2709-bound peptide repertoires are largely overlapping. Thus, to the extent to which linkage of HLA-B27 with AS is related to the peptide-presenting properties of this molecule, our results would imply that peptides within a relatively small fraction of the HLA-B27-bound peptide repertoire influence susceptibility to this disease.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Facultad de Ciencias, Spain.
authors.forename: M
authors.initials: M
authors.lastname: García-Peydró
authors.forename: M
authors.initials: M
authors.lastname: Martí
authors.forename: J A
authors.initials: JA
authors.lastname: López de Castro
mesh_terms: D000483:Alleles; D019943:Amino Acid Substitution / Q000235:genetics / Q000276:immunology; D002999:Clone Cells; D003601:Cytotoxicity Tests, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology*; D015796:HLA-B27 Antigen / Q000235:genetics / Q000276:immunology*; D006801:Humans; D010455:Peptides / Q000235:genetics / Q000276:immunology; D017354:Point Mutation; D013167:Spondylitis, Ankylosing / Q000235:genetics / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism; D014162:Transfection
chemical_list: D018984:Epitopes, T-Lymphocyte; D015796:HLA-B27 Antigen; D010455:Peptides