title: HLA class II polymorphisms determine responses to bacterial superantigens.
abstract: The excessive immunological response triggered by microbial superantigens has been implicated in the etiology of a wide range of human diseases but has been most clearly defined for the staphylococcal and streptococcal toxic shock syndromes. Because MHC class II presentation of superantigens to T cells is not MHC-restricted, the possibility that HLA polymorphisms could influence superantigenicity, and thus clinical susceptibility to the toxicity of individual superantigens, has received little attention. In this study, we demonstrate that binding of streptococcal and staphylococcal superantigens to HLA class II is influenced by allelic differences in class II. For the superantigen streptococcal pyrogenic exotoxin A, class II binding is dependent on DQ alpha-chain polymorphisms such that HLA-DQA1*01 alpha-chains show greater binding than DQA1*03/05 alpha-chains. The functional implications of differential binding on T cell activation were investigated in various experimental systems using human T cells and murine Vbeta8.2 transgenic cells as responders. These studies showed quantitative and qualitative differences resulting from differential HLA-DQ binding. We observed changes in T cell proliferation and cytokine production, and in the Vbeta specific changes in T cell repertoire that have hitherto been regarded as a defining feature of an individual superantigen. Our observations reveal a mechanism for the different outcomes seen following infection by toxigenic bacteria.
authors.affiliation: Department of Infectious Diseases, Faculty of Medicine, Imperial College, Department of Immunology, Guy's, Kings and St. Thomas' School of Medicine, London, United Kingdom.
authors.forename: Martin
authors.initials: M
authors.lastname: Llewelyn
authors.forename: Shiranee
authors.initials: S
authors.lastname: Sriskandan
authors.forename: Mark
authors.initials: M
authors.lastname: Peakman
authors.forename: David R
authors.initials: DR
authors.lastname: Ambrozak
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Douek
authors.forename: William W
authors.initials: WW
authors.lastname: Kwok
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cohen
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Altmann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001422:Bacterial Adhesion / Q000276:immunology; D001426:Bacterial Proteins; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005098:Exotoxins / Q000276:immunology / Q000378:metabolism; D006683:HLA-DQ Antigens / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation / Q000235:genetics; D008565:Membrane Proteins; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic / Q000502:physiology*; D011485:Protein Binding / Q000276:immunology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis; D013297:Streptococcus pyogenes / Q000276:immunology / Q000472:pathogenicity; D018089:Superantigens / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000382:microbiology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D005098:Exotoxins; D006683:HLA-DQ Antigens; D008565:Membrane Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; C117980:SpeA protein, Streptococcus pyogenes; D018089:Superantigens; C027951:erythrogenic toxin