Time course of IL-6 and TNF alpha release during endotoxin-induced endotoxin tolerance in rats.

Development of endotoxin tolerance in rats induced by repeated application of low dosages of endotoxin is associated with repeatable IL-6 formation, reversible drop in white blood cells, pronounced consumption of platelets, gradual formation of alpha 2M as an example of acute phase proteins, and flattening TNF alpha formation. In the status of full tolerance the TNF alpha release is completely eliminated. Inhibition of TNF alpha biosynthesis and induction of acute phase protein formation by IL-6 are discussed as possible factors in the development of endotoxin tolerance.