IL 1 causes

Ref Robbins 9/e p87 IL-1 is intensely produced by tissue macrophages, monocytes, fibroblasts, and dendritic cells, but is also expressed by B lymphocytes, NK cells, microglia, and epithelial cells. They form an impoant pa of the inflammatory response of the body against infection. These cytokines increase the expression of adhesion factors on endothelial cells to enable transmigration (also called diapedesis) of immunocompetent cells, such as phagocytes, lymphocytes and others, to sites of infection. They also affect the activity of the hypothalamus, the thermoregulatory center, which leads to a rise in body temperature (fever) . That is why IL-1 is called an endogenous pyrogen. Besides fever, IL-1 also causes hyperalgesia (increased pain sensitivity), vasodilation and hypotension.