Interleukin-1 beta (IL1B) belongs to the IL-1 family. Interleukin 1 (IL-1) is a family of polypeptide cytokines consisting of two agonists, IL-1 alpha (IL-1F1) and IL-1 beta (IL-1F2) encoded by two distinct genes and perform identical biological functions. IL-1 stimulates thymocyte proliferation by inducing IL-2 release, B-cell maturation and proliferation, and fibroblast growth factor activity. IL-1 proteins are involved in the inflammatory response. It is identified as endogenous pyrogens, and is reported to stimulate the release of prostaglandin and collagenase from synovial cells.