http://www.creativebiomart.net/description_382845_12.htm

IL1 is an important prototypic pro-inflammatory cytokine that affects multiple cell types, often in concert with another cytokine, tumor necrosis factor (TNF). There are two forms of IL1, IL1 alpha;. and IL1 beta, whose function are mediated by the two specific receptors on the cell surfaces. The IL1 receptor antagonist (IL1RA), formerly called the IL1 inhibitor, is a member of the IL1 cytokine family which binds to the same receptor (IL1R) as IL1, and thus prevents IL1 from signal transduction without interaction with the IL1 molecules. In terms of protein similarities,IL1RA is more closely related to IL1 beta; than it is to IL1 alpha;. IL1RA modulates a variety of IL1-related immune and inflammatory responses, and accordingly, the balance between IL1 and IL1Ra in local tissues plays an important role in the susceptibility to and severity of many diseases. IL1RA is suggested to have possible therapeutic applications in treatment of sepsis, rheumatoid arthritis, and chronic myelogenous leukemia. Four alternatively spliced transcript variants encoding distinct isoforms have been identified, and the isoform 1 of IL1RA is secreted from monocytes, macrophages, neutrophils, and other cells.