Superantigens: the paradox of T-cell activation versus inactivation.
Superantigens are interesting for several reasons. They exhibit unusual T-cell activation characteristics, they allow to follow in vivo ligand-reactive T cells, they cause T-cell-mediated shock symptoms and they may be causally involved in certain human diseases. This review focuses on the paradox of T-cell activation versus T-cell inactivation as caused by bacterial superantigens in vivo. T-cell activation leads to the acute release of toxic concentrations of lymphokines including tumor necrosis factor alpha/beta, gamma-interferon, interleukin (IL)-2, IL-4 and IL-10. T-cell inactivation mirrors induction of anergy, T-cell receptor downregulation, and that of CD2, CD4 and CD8 cell surface molecules, as well as of apoptosis. Two waves of apoptosis cripple the T-cell repertoire of superantigen-reactive T cells, an immediate one being induced within 24 h and a late one occurring at days 3-4. In between, clonal expansion of anergic ligand-reactive T cells takes place.
Miethke
T
T
Institute of Medical Microbiology and Hygiene, Technical University of Munich, Germany.
Wahl
C
C
Heeg
K
K
Wagner
H
H
D015536:Down-Regulation; D006801:Humans; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis; D011948:Receptors, Antigen, T-Cell / Q000187:drug effects / Q000378:metabolism; D018089:Superantigens / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
D008222:Lymphokines; D011948:Receptors, Antigen, T-Cell; D018089:Superantigens