Potentiation of lethal endotoxin shock by streptococcal pyrogenic exotoxin in rabbits: possible relevance of hyperreactivity of macrophages to endotoxin.

Streptococcal pyrogenic exotoxin (SPE) potentiates lethal shock induced by endotoxin. We have previously reported that macrophages derived from SPE-treated rabbits showed hyperreactivity to endotoxin, and that the effect of SPE on macrophages was mediated by a lymphokine(s). Here we show that culture supernatants of SPE-stimulated lymphocytes, when administered into rabbits three hours before or together with endotoxin, potentiate a variety of endotoxin-induced pathophysiological changes and even lethal shock. These results suggest that SPE-induced lymphokine(s) mediates the potentiating effect of SPE on the lethal endotoxin shock through enhancing endotoxin reactivity of macrophages which play the central role in mediating endotoxin toxicity.