title: Cellular and biochemical responses of human T lymphocytes stimulated with streptococcal M proteins.
abstract: Purified group A streptococcal M proteins, pep M5 and pep M6, bearing heart cross-reactive epitopes were compared with pep M24, which lacks such epitopes, in their ability to induce functional differentiation of human T lymphocytes. Lymphocytes activated by pep M5 and pep M6 demonstrated cytotoxic activity against cultured heart cells, whereas pep M24-activated cells differentiated into suppressor T cells, which specifically blocked cytotoxic T lymphocytes against cultured human myocardial cells and not NK cell activity against K562 cells. Pep M5 and not pep M24 induced an increase in the number of CD4, 4B4, helper/inducer T cells. In addition, these M proteins appear to induce different biochemical changes in T lymphocytes. Both pep M5 and pep M24 induced the phosphorylation of a 35-kDa cytoplasmic protein; however, only pep M5 induced the phosphorylation of a 28-kDa membrane protein, primarily in CD4 T cells. These data indicate that the virulent M protein Ag of group A streptococci may exert their effect on the human immune system via different mechanisms. Determining these mechanisms and the biochemical pathways involved in T cell differentiation triggered by these Ag may be important in understanding the pathogenesis of post-streptococcal diseases.
authors.affiliation: Veterans Administration Medical Center, Memphis, Tennessee 38104.
authors.forename: M
authors.initials: M
authors.lastname: Kotb
authors.forename: H S
authors.initials: HS
authors.lastname: Courtney
authors.forename: J B
authors.initials: JB
authors.lastname: Dale
authors.forename: E H
authors.initials: EH
authors.lastname: Beachey
mesh_terms: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000494:pharmacology*; D002352:Carrier Proteins; D003429:Cross Reactions; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D009206:Myocardium / Q000276:immunology; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; C014689:streptococcal M protein; D014443:Tyrosine; D012694:Serine