Does staphylococcal enterotoxin B bind directly to murine T cells?
We have investigated the binding potential of staphylococcal enterotoxin B (SEB) to murine T cells using the induction of early activation events in Th1 and Th2 T-cell clones in the absence of antigen-presenting cells (APC) as indicators of direct interactions between SEB and the T-cell receptor (TcR). We consistently found that concanavalin A (Con A) induced rises in intracellular free calcium as well as inositol phosphate accumulation in APC-free T-cell clones. However, SEB uniformly failed to induce either calcium fluxes or inositol phosphate turnover in Th1 and Th2 T-cell clones in the absence of APC. In addition, we have used proliferation assays to show that (i) T-cell clones prepulsed with SEB did not respond when APC were added, (ii) APC-independent T-cell clones responded to soluble anti-TcR antibodies but not to SEB in the absence of APC, and (iii) SEB coupled to Sepharose beads did not stimulate T-cell clones in the absence of APC. Taken together our results argue against SEB binding to the TcR without the participation of MHC class II molecules.
Department of Immunology, Medical School, University of Newcastle upon Tyne, U.K.
W
W
Qasim
M A
MA
Kehoe
J H
JH
Robinson
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000276:immunology; D002999:Clone Cells / Q000276:immunology; D004768:Enterotoxins / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008815:Mice, Inbred Strains; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*
D004768:Enterotoxins; D007295:Inositol Phosphates; D011948:Receptors, Antigen, T-Cell; C031818:enterotoxin B, staphylococcal; D002118:Calcium