Human IL-1 alpha Carrier-Free Recombinant Protein, eBioscience?. IL-1 alpha (Interleukin-1 alpha) is a proinflammatory cytokine expressed by monocytes, macrophages, and dendritic cells. IL-1 alpha is coded by the IL1A gene and signals through two receptors, IL-1RI and IL-1RII, both of which are shared with IL-1 beta. IL1A is located on the q arm on chromosome 2 at position 13. IL-1 alpha plays an important role in innate host defense by triggering the production of other proinflammatory cytokines in target cells and initiating acute-phase responses. IL-1 alpha activity can be moderated by IL-1 Receptor Antagonist (IL-1RA), a protein produced by many cell types that blocks receptor binding through competitive inhibition. IL-1 alpha is