ABSTRACT
Bacterial products including endotoxin have been administered to humans over the past century as therapeutic, diagnostic, and experimental agents. The acute phase response is the early immediate host response to infection or tissue injury and results in fever, leukocytosis, changes in vascular permeability, and altered metabolic responses in various organs. Humoral defense mechanisms are rapidly activated after endotoxin administration. The contact system composed of Factors XII, XI, prekallikrein, and high molecular weight kininogen amplifies several host inflammatory responses including the initiation of coagulation via the intrinsic pathway, activation of plasminogen and neutrophils, as well as the generation of bradykinin, a potent vasodilator. Cytokines serve as important links to amplify the inflammatory response initiated by endotoxin. Hepatic synthetic function is rapidly upregulated in response to endotoxin. Endotoxin has been implicated in the pathogenesis of gram-negative bacterial pneumonia as well as the development of acute and chronic lung inflammation due to occupational dust exposure.
