Interleukin 1 receptor antagonist (IL-1ra) is a member of the interleukin 1 (IL-1) family of cytokines produced by secretion from a variety of cells including immune cells, epithelial cells, and adipocytes, and is a natural inhibitor of the pro-inflammatory effects of IL-1β. IL-ra is a mediator that binds non-efficiently to the interleukin 1 receptor (IL-1R) on the surface of cells. In turn, IL-1R is also the receptor that binds IL-1, so IL-1ra prevents IL-1 from sending signals to the cell. This protein inhibits IL-1α and IL-1β activity and regulates a variety of IL-1-associated immune and inflammatory responses.Polymorphisms in the IL-1RN gene have been associated with an increased risk of osteoporotic fractures and gastric cancer. Mutations in this gene will lead to the development of a rare disease known as IL-1ra deficiency. Mutations in this gene are also associated with the risk of developing schizophrenia. It is used to treat rheumatoid arthritis.