Interleukin 1, a prototypic pleiotropic lymphokine.

Interleukin 1 (IL-1) is an endogenous mediator produced by monocytes/macrophages, endothelial cells and other cell types. It was originally identified as the main endogenous pyrogen. It was later found that IL-1 was identical to other factors that had been defined leukocytic endogenous mediator, lymphocyte activating factor. It is now clear that IL-1 has two main aspects. On one side it is an immunostimulatory molecule and on the other side is a mediator of shock and inflammation. As an immunostimulating molecule, IL-1 is a potential immuno-modulating drug, while with respect to its proinflammatory action it might be important to identify antagonists or inhibitors that could be useful in the therapy of chronic inflammatory diseases.