title: Cross-reactive T cell clones from unrelated individuals reveal similarities in peptide presentation between HLA-B27 and HLA-DR2.
abstract: HLA-B27- responder cells were stimulated in vitro with B*2705+ lymphoblastoid cell lines and alloreactive CTL clones were obtained by limiting dilution. Of the CD3+ CD4-CD8+ HLA-B27-specific CTL clones obtained, two of them, possessing the same TCR, cross-reacted with HLA-DR2. The fine specificity of these CTL was established with HLA-B27 and HLA-DR2 subtypes. They recognized the B*2701 to B*2706 subtypes, but only DR2Dw2. Lysis of DR2+ target cells was specifically inhibited by anti-CD3, anti-class II, and anti-DR mAb, but not with an anti-CD8 antibody. The monoclonal nature of the cross-reaction was established by the mutual inhibition of HLA-B27 and DR2Dw2 cells in cold target competition experiments. The DR2 protein involved in the cross-reaction was the heterodimer carrying the B5*0101 product, as shown by using L cell transfectants expressing each of the two molecules encoded in the DR2Dw2 haplotype. A correlation between the fine specificity of these CTL clones and the amino acid sequences of HLA-B27 and HLA-DR2 subtypes revealed a shared structural motif between HLA-B27 and the DR2 B5*0101 chain, which could be related to the observed cross-reaction. This motif was contributed for by several residues located in adjacent beta strands, at the floor of the peptide-binding site. The contribution of two of these residues, as well as other beta-pleated sheet residues to HLA-B27 allorecognition by the cross-reactive CTL clones was directly demonstrated with site-directed mutants. These results suggest that the dual reactivity pattern reflects presentation of identical or structurally related peptide by HLA-B27 and HLA-DR2Dw2. As T cell cross-reactivity between HLA-B27 and HLA-DR2 was previously found in cells from an unrelated individual the results reported here are likely to reflect an intrinsic property of HLA-B27, rather than the fortuitous finding of a rare clonal reaction pattern. We speculate on the potential implications of these results for the pathogeny of HLA-B27-associated spondyloarthropathies.
authors.affiliation: Centro de Biologia Molecular, Universidad Autónoma de Madrid, Spain.
authors.forename: D
authors.initials: D
authors.lastname: López
authors.forename: D F
authors.initials: DF
authors.lastname: Barber
authors.forename: J A
authors.initials: JA
authors.lastname: Villadangos
authors.forename: J A
authors.initials: JA
authors.lastname: López de Castro
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001483:Base Sequence; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D017252:CD3 Complex / Q000502:physiology; D016827:CD8 Antigens / Q000502:physiology; D002460:Cell Line; D002999:Clone Cells; D003429:Cross Reactions; D003601:Cytotoxicity Tests, Immunologic; D000939:Epitopes; D015796:HLA-B27 Antigen / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D015802:HLA-DR2 Antigen / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007133:Immunoglobulin Joining Region / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D016827:CD8 Antigens; D000939:Epitopes; D015796:HLA-B27 Antigen; D015802:HLA-DR2 Antigen; D007133:Immunoglobulin Joining Region; D010455:Peptides; D011948:Receptors, Antigen, T-Cell