Interleukin 1 alpha (IL-1α) is a member of the IL-1 family and a dual-function cytokine. Both the unprocessed precursor and a processed IL-1α protein signal through IL-1 receptor type 1 (IL-1R1). Various cells, including keratinocytes, thymic epithelium, hepatocytes, endothelial cells, fibroblasts, and the epithelial cells of mucous membranes, have high levels of intracellular IL-1α precursor. The precursor is also expressed on the surface of monocytes and B lymphocytes (Netea et al.). IL-1α recruits infiltrating cells to a site of injury during necrosis and plays an important role during processes of sterile inflammation (Cohen et al.; Rider et al.). During hypoxia, IL-1α contributes to angiogenesis (Carmi et al.). Studies in mice show that IL-1α is produced by microglia-like cells after ischemic brain injury, which contributes to the inflammation (Luheshi et al.).