Reactivity of human gamma delta T cells to staphylococcal enterotoxins: a restricted reaction pattern mediated by two distinct recognition pathways.
Staphylococcal enterotoxins (SEs) are known superantigens for T cells expressing the alpha beta T-cell receptor (TCR). They bind to MHC class II molecules on antigen-presenting cells and can subsequently trigger T-cell responses by binding to V beta-gene products. The reactivity of gamma delta T cells with enterotoxins is less well defined although both proliferative and cytotoxic responses have been described. In the present study we have tested the cytotoxic reactivity of a panel of 41 gamma delta T-cell clones against target cells coated with the enterotoxins SEA, SEB, SEC1, SEC2, SEC3, SED, SEE or TSST. Three reaction patterns were observed with the gamma delta T-cell clones: (1) clones that specifically lysed SEA-coated target cells only; (2) clones that specifically lysed SEE-coated target cells only, and (3) clones that specifically lysed SEA-coated target cells only in the presence of certain human sera. The presence of SEA-specific antibodies in such human sera could be demonstrated. Moreover, gamma delta T-cell clones of this third category expressed the IgG FcRIII (CD16) which indicates that these clones are capable of mediating antibody-dependent cellular cytotoxicity towards SEA-coated target cells. Thus, the cytotoxic response of gamma delta T cells to SEs is mediated by two distinct pathways: an antibody-independent and an antibody-dependent pathway. The antibody-independent reactivity of gamma delta T cells was directed to either SEA or SEE, whereas antibody-dependent reactivity was found only towards SEA. The capacity of gamma delta T-cell clones to respond to stimulation with SEs, combined with their high cytolytic capacity in vitro, suggests that these cells can be involved in SE-directed immune responses and efficiently kill SE-coated target cells in vivo.
Rust
C
C
Department of Immunohaematology and Bloodbank, University Hospital, Leiden, The Netherlands.
Orsini
D
D
Kooy
Y
Y
Koning
F
F
D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004768:Enterotoxins / Q000276:immunology*; D006801:Humans; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D017452:Receptors, IgG; D013211:Staphylococcus aureus / Q000276:immunology*
D004768:Enterotoxins; D016692:Receptors, Antigen, T-Cell, gamma-delta; D017452:Receptors, IgG; C049463:enterotoxin E, Staphylococcal; C026066:enterotoxin A, Staphylococcal