Interleukin-1 (IL-1) is an extracellular peptide of 17 kDa that designates two proteins, IL-1α and IL-1β. IL-1β is produced by activated macrophages as a proprotein, which is proteolytically processed to its active form by caspase 1 (CASP1/ICE). This cytokine is an important mediator of the inflammatory response, and is involved in a variety of cellular activities, including cell proliferation, differentiation, and apoptosis.The interleukin-1 (IL-1) species represent an important family of biologically active mono nuclear cell-derived proteins which are involved in inflammatory reactions and in immune responses.
Increased production of IL-1β causes a number of different autoinflammatory syndromes, most notably the monogenic conditions referred to as CAPS, due to mutations in the inflammasome receptor NLRP3 which triggers processing of IL-1β.