title: Staphylococcal enterotoxin-mediated human T-T cell interactions.
abstract: Staphylococcal enterotoxins (SE) are known to stimulate a large proportion of T cells. SE bind to MHC-class II molecules on APC and a particular segment of certain TCR V beta and V gamma gene products. Resting human T cells do not express HLA class II Ag and therefore cannot present SE to T cells. Activated human T cells, however, do express HLA-DR, -DP, and -DQ Ag and could consequently serve as APC for SE. As such, local immune responses to SE might be regulated and/or abrogated by SE-mediated T-T cell interactions leading to T cell destruction. We have investigated if such SE-mediated T-T cell interactions can occur in vitro using human cytolytic TCR-alpha beta+ and TCR-gamma delta+ T cell clones. We demonstrate that the TCR-alpha beta+ T cell clones can efficiently present staphylococcal enterotoxin A (SEA) to each other: T cell clones coated with SEA are lysed by SEA-reactive T cell clones but not by a SEA-nonreactive T cell clone. Furthermore, the SEA-reactive TCR-alpha beta+ clones (but not the SEA-nonreactive clone) destruct themselves in the presence of SEA at low concentrations of SEA (less than 0.01 microgram/ml). Also, SEA-coated T cell clones can induce proliferative responses although such responses are much weaker than those induced when B cells are used as stimulator cells. In contrast, the SEA-reactive TCR-gamma delta+ T cell clones are resistant to autokilling in the presence of SEA and they do not lyse SEA-coated TCR-gamma delta+ targets. However, such targets can be lysed by TCR-alpha beta+ effector cells. These results indicate that TCR-gamma delta+ cells are relatively resistant to lysis and that during local nonspecific immune responses triggered by SE, which induces HLA-class II expression by the responding T cells, SE-mediated T-T cell interactions may play a role in the regulation and/or abrogation of these immune responses.
authors.affiliation: Department of Immunohematology and Bloodbank, University Hospital, Leiden, The Netherlands.
authors.forename: F
authors.initials: F
authors.lastname: Koning
authors.forename: C
authors.initials: C
authors.lastname: Rust
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D004768:Enterotoxins / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D004768:Enterotoxins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; C026066:enterotoxin A, Staphylococcal