Interleukin-6, Its Hepatic Receptor and the Acute Phase Response of the Liver

The acute phase response is the answer of the organism to disturbances of its homeostasis due to infection, tissue injury, neoplastic growth, or immunological disorders. It is thought to be beneficial to die injured organism and its aim is the restoration of the disturbed physiological homeostasis. There is first a local reaction at the site of injury characterized by the aggregation of platelets, clot formation, dilation and leakage of blood vessels, accumulation of granulocytes and mononuclear cells and the activation of endothelial cells, fibroblasts, monocytes, and macrophages, which in turn release inflammatory cytokines such as interleukin-1, interleukin-6, interleukin-8, tumor necrosis factor a, and interferons. These mediators act via specific surface receptors on different target cells and lead to a systemic reaction of the organism characterized by fever, leukocytosis, increases in the erythrocyte sedimentation rate, in the secretion of ACTH and glucocorticoids, the activation of complement and clotting cascades, and in dramatic changes in the concentrations of some plasma proteins designated as acute phase proteins [reviews 1–3].