The activation of bone marrow macrophages 24 hours after thermal injury.

We determined the effect of thermal injury on the in vitro production of the immunoactive substances tumor necrosis factor, interleukin 1, prostaglandin E2, and complement component C3 by lipopolysaccharide-stimulated guinea pig bone marrow macrophages and on the cytotoxicity of these cells. Macrophages from burned animals produced different amounts of these mediators compared with unburned animals at certain culture times, suggesting that thermal injury could program the bone marrow cells to respond differently from normal cells to in vitro stimulation with lipopolysaccharide. Also, the macrophages from burned animals displayed greater cytotoxicity towards L929 target cells. These results suggest that there is a complex interaction among cellular secretory products, especially after thermal injury, that may be important in host defense.