title: Early activation events differentiate the reactivity of two T-cell families to Staphylococcus enterotoxin A.
abstract: Analysis of early activation events in two SEA responsive T-cell families demonstrated that low doses of SEA induced CD4+Vbeta22 T-cells to down-regulate their TCR and express CD69, considerably earlier than CD4+Vbeta5 T-cells. The rapid down-regulation of Vbeta22 TCR led to its proliferation, whereas even a 10-fold higher dose of toxin induced only a partial down-regulation of Vbeta5 TCR. Stimulation with SEA induced a significantly higher percentage of Vbeta22 T-cells to produce IFN-gamma compared to Vbeta5 T-cells. SEAF47A, a mutant of SEA, known to have a lower binding affinity for the MHC class II molecule, failed to activate Vbeta5 T-cells whereas Vbeta22 T-cell activation was slightly decreased. Hence, early activation events highlighted the differential requirements of T-cell families to respond to SEA.
authors.affiliation: Laboratoire d' Immunologie, Institut de Recherche Clinique de Montréal, 110 Avenue des Pins Ouest, Montréal, Que, Canada H2W 1R7. sdsouza@pasteur.be
authors.forename: Sushila
authors.initials: S
authors.lastname: D'Souza
authors.forename: Helen
authors.initials: H
authors.lastname: McGrath
authors.forename: Rafick P
authors.initials: RP
authors.lastname: Sékaly
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000187:drug effects; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis / Q000187:drug effects; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology*; D002478:Cells, Cultured; D015536:Down-Regulation; D004768:Enterotoxins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D007369:Interferon Inducers / Q000276:immunology / Q000494:pharmacology*; D007371:Interferon-gamma / Q000096:biosynthesis / Q000187:drug effects; D037181:Lectins, C-Type; D009154:Mutation; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000187:drug effects / Q000276:immunology*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D004768:Enterotoxins; D007369:Interferon Inducers; D007371:Interferon-gamma; D037181:Lectins, C-Type; D016693:Receptors, Antigen, T-Cell, alpha-beta; D000099192:CD69 Antigens; C026066:enterotoxin A, Staphylococcal