IL-1α is a monomeric protein belonging to the IL-1 family which also comprises interleukin-1β (IL-1β). Both IL-1α and IL-1β bind to the same receptor and therefore also show similar if not identical biological activities. A key function of IL-1α and IL-1β is the stimulation of T helper (Tʜ) cells by inducing IL-2 release. Furthermore, IL-1 is involved in B cell maturation and proliferation and has fibroblast growth factor activity. IL-1, in combination with other cytokines, plays a significant role in the the development of inflammatory responses. IL-1α is the predominant IL-1 form in mouse. In mice, a transition from IL-1β to IL-1α production during maturation of monocytes into inflammatory macrophages can be observed. Murine Tʜ17 cells develop in response to IL-1 and other cytokines.