title: Further clonal expansion of T cells upon rechallenge of superantigen staphylococcal enterotoxin A.
abstract: Superantigens are known to induce clonal anergy and/or deletion in reactive T cells peripherally. This study was undertaken to investigate the T-cell status early after exposure to staphylococcal enterotoxin A (SEA) in vivo and in vitro. At the peak of clonal expansion following the administration of 5 microg SEA (i.e., 2 days after the injection), C57BL/6 mice were rechallenged with the same dose of SEA in vivo. The secondary stimulation augmented clonal expansion of the T cells bearing Vbeta3 and Vbeta11 in both CD4+ and CD8+ populations. In vitro restimulation of the spleen cells taken from the SEA-primed mice also induced further expansion of the Vbeta3+ T cells during 2 days of culturing, whereas without restimulation, a marked reduction of Vbeta3+ T cells occurred. The spleen cells from the SEA-primed mice were hyper-reactive to in vitro restimulation with SEA as measured by 3H-TdR uptake on day 1 of culturing, but augmented proliferation leveled off thereafter. By day 3, the values of 3H-TdR uptake were less than 20% of those of the controls in which spleen cells from native mice were stimulated with SEA in vitro. These results suggest that T cells exposed to SEA in vivo are still capable of proliferating upon SEA rechallenge, but subsequently, the proliferation starts to wane.
authors.affiliation: Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Showa-ku, Aichi, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aoki
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshikai
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000276:immunology; D016827:CD8 Antigens / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002478:Cells, Cultured; D017637:Clonal Deletion / Q000276:immunology; D004768:Enterotoxins / Q000008:administration & dosage / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D013154:Spleen / Q000276:immunology; D018089:Superantigens / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000382:microbiology*
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D004768:Enterotoxins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens; C026066:enterotoxin A, Staphylococcal