title: Characterization of unique human TCR V beta specificities for a family of streptococcal superantigens represented by rheumatogenic serotypes of M protein.
abstract: The M protein of Streptococcus pyogenes plays a major role in the virulence of these bacteria. Members of the M protein superfamily are characterized by the presence of tandem segments of repeated amino acid sequences. The NH2-terminal end of the M proteins is a hypervariable region that harbors the type-specific epitopes of the molecule. Pepsin cleaves the molecule into a highly conserved carboxyl terminal half and a variable amino terminal portion referred to as pep M. In some individuals, infection with certain serotypes of group A streptococci is followed by autoimmune disorders such as rheumatic fever and acute glomerulonephritis. The serotypes of M protein that show a high degree of association with acute rheumatic fever are referred to as rheumatogenic serotypes. We have reported that one such serotype, type 5, is a superantigen to human T cells, specifically stimulating T cells bearing V beta 2, V beta 4, and V beta 8 elements. Here we extend our studies by examining other rheumatogenic serotypes for superantigenic properties. Studies with types 6, 18, 19, and 24 M proteins revealed that they are all superantigens to human T cells. The specificity to V beta 4 was shared by the rheumatogenic M proteins tested; however, each pep M serotype has its unique characteristic set of V beta specificity and these are distinct from those reported for the streptococcal pyrogenic exotoxins. The non-rheumatogenic serotype, pep M2, only stimulated V beta 2-bearing T cells. This study establishes that the structurally related M proteins represent a family of streptococcal superantigens analogous to the structurally related family of staphylococcal enterotoxin superantigens.
authors.affiliation: Veteran's Administration Medical Center, Memphis, TN 38104.
authors.forename: R
authors.initials: R
authors.lastname: Watanabe-Ohnishi
authors.forename: J
authors.initials: J
authors.lastname: Aelion
authors.forename: L
authors.initials: L
authors.lastname: LeGros
authors.forename: M A
authors.initials: MA
authors.lastname: Tomai
authors.forename: E V
authors.initials: EV
authors.lastname: Sokurenko
authors.forename: D
authors.initials: D
authors.lastname: Newton
authors.forename: J
authors.initials: J
authors.lastname: Takahara
authors.forename: S
authors.initials: S
authors.lastname: Irino
authors.forename: S
authors.initials: S
authors.lastname: Rashed
authors.forename: M
authors.initials: M
authors.lastname: Kotb
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000276:immunology*; D001483:Base Sequence; D002352:Carrier Proteins; D005098:Exotoxins / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000502:physiology*; D012213:Rheumatic Fever / Q000209:etiology*; D012680:Sensitivity and Specificity; D016415:Sequence Alignment; D013291:Streptococcus / Q000276:immunology*; D018089:Superantigens / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005098:Exotoxins; D008565:Membrane Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; C117980:SpeA protein, Streptococcus pyogenes; D018089:Superantigens; C027951:erythrogenic toxin; C014689:streptococcal M protein