Acquired resistance to superantigen-induced T cell shock. V beta selective T cell unresponsiveness unfolds directly from a transient state of hyperreactivity.

TCR V beta selective T cell activation and systemic release of T cell-derived lymphokines causing lethal shock in D-galactosamine (D-Gal)-sensitized mice depicts only one facet of in vivo challenge with the superantigen staphylococcal enterotoxin B (SEB). An immediate second major aspect represents the induction of peripheral unresponsiveness in SEB-reactive V beta 8+ T cells. SEB causes in vivo within 4 h resistance to an otherwise lethal challenge with SEB plus D-Gal, as well as to a challenge with the heterologous ligand toxic shock syndrome toxin 1 plus D-Gal. Contrary to the first challenge, no serum-borne IL-2 and TNF are discernible during the second challenge. On the other hand, kinetic analyses in vitro of LN cells draining the site of the first in vivo challenge indicate that SEB-reactive T cells develop via a transient state of hyperreactivity into a profound state of ligand-specific unresponsiveness. Yet unresponsive V beta 8+ T cells express IL-2R and are responsive to the growth-promoting effect of IL-2. Cyclosporin A does not impair sequential induction of hyperreactivity and unresponsiveness with concomitant IL-2R expression, but effectively blocks systemic IL-2 and TNF release during the initial hyperreactive phase. Taken together, the in vitro data imply that ligand-specific hyperreactivity followed immediately by ligand-specific unresponsiveness represents a hallmark of in vivo challenge with the superantigen SEB. The in vivo data suggest the existence of additional suppressive elements masking the ligand specificity of the state of unresponsiveness induced by SEB.