Interleukin 10 reduces the release of tumor necrosis factor and prevents lethality in experimental endotoxemia.

Because of its ability to efficiently inhibit in vitro cytokine production by activated macrophages, we hypothesized that interleukin (IL) 10 might be of particular interest in preventing endotoxin-induced toxicity. We therefore examined the effects of IL-10 administration before lipopolysaccharide (LPS) challenge in mice. A marked reduction in the amounts of LPS-induced tumor necrosis factor (TNF) release in the circulation was observed after IL-10 pretreatment at doses at low as 10 U. IL-10 also efficiently prevented the hypothermia generated by the injection of 100 micrograms LPS. Finally, pretreatment with a single injection of 1,000 U IL-10 completely prevented the mortality consecutive to the challenge with 500 micrograms LPS, a dose that was lethal in 50% of the control mice. We conclude that IL-10 inhibits in vivo TNF secretion and protects against the lethality of endotoxin in a murine model of septic shock.