The gene IL-1RA (interleukin-1 receptor antagonist) is mapped to human chromosome 2q. It belongs to the IL-1 (interleukin 1) family of proteins. The encoded protein has a TIR (Toll/IL-1 receptor) domain. IL-1RA is produced by corneal epithelial cells, monocytes, neutrophils, macrophages and fibroblasts. It is a naturally occurring inflammatory inhibitor protein. Recombinant human IL-1RA is a 17.2kDa protein consisting of 153 amino acid residues.
Interleukin-1 receptor antagonist (IL-1RA) inhibits the activity of IL-1α (interleukin 1 α) and IL-1β (interleukin 1 β) by competitively blocking binding to their type I and type II receptors. Therapeutically, IL-1RA may help in the treatment of sepsis, rheumatoid arthritis, chronic myelogenous leukemia, asthma, psoriasis, and inflammatory bowel disease. Low production of IL-1RA is observed in HIV-1 (human immunodeficiency virus 1)-infected dendritic cells.