Interleukin 1, alpha (IL-1α) is a pleiotropic cytokine involved in inflammation, immunity, hematopoiesis, and is a pro-apoptotic protein. Stimulates thymocyte proliferation by inducing IL-2 release, B-cell maturation and proliferation, and fibroblast growth factor activity. Has pro-inflammatory properties, also promoting fever and sepsis, and has been implicated in multiple diseases related to these symptoms. Interacts with TNF, another pro-inflammatory cytokine.