The most prominent members of the interleukin-1 (IL-1) superfamily are IL-1α and IL-1β. IL-1α was reported to be more widely and constitutively expressed and has intracellular functions, but also acts locally in a membrane-bound form by activating IL-1R1. Additionally, passive release of IL-1α upon cell death can trigger a sterile inflammatory response to dying cells. Interleukin 1 is responsible for the production of inflammation, as well as the promotion of fever and sepsis.