Effects of endotoxin in murine burns.

Previous studies in our laboratory have demonstrated the protective effect of the spleen in murine burns. Since the spleen is a reservoir of the reticuloendothelial system (RES) and since small doses of endotoxin stimulate RES activity, the purpose of this investigation was to perform studies to determine whether endotoxin administration will further augment burn protection in splenectomized and nonsplenectomized animals. Swiss white mice were randomly assigned to one of two groups. One group was splenectomized and the other received a sham splenectomy. Twelve weeks later, under pentobarbital anesthesia, all animals were burned uniformly on the lower back. Log doses of Escherichia coli endotoxin or an equal volume of saline were administered intraperitoneally immediately after thermal injury. Severity of burns at 24 hours was assessed from gross and microscopic appearances using a grading scale of 0 (normal) to 4 (severe). Splenectomized controls receiving saline had more severe burns than the sham-splenectomized controls. Endotoxin decreased burn severity in both splenectomized and non-splenectomized mice. However, endotoxin afforded greater burn protection in the splenectomized mice when compared with the non-splenectomized animals.