Interleukin 1 receptor antagonist

The IL-1 receptor antagonist (IL-1RA) was initially called the IL-1 inhibitor and was discovered separately in 1984 by two independent laboratories. IL-1RA, is an agent which binds to the same receptor on the cell surface as IL-1, and thus prevents IL-1 from sending a signal to that cell. It is used in the treatment of rheumatoid arthritis, an autoimmune disease in which IL-1 plays a key role. It is commercially produced as anakinra, which is a human recombinant form of IL-1RA. In terms of protein similarities, IL-1β is more closely related to IL-1RA than it is to IL- 1α. The amino acids that are identical between mature human IL-1α and mature IL-1β is 22% while it is 26% when comparing IL-1β to IL-1RA and only 18% when comparing IL-1α to IL-1RA.