Interleukin-1beta (IL-1ß) is a proinflammatory cytokine produced in response to inflammatory agents by a variety of cells, including monocytes, macrophages, and dendritic cells (DCs). IL-1ß and IL-1a are two distinct and independently regulated gene products that comprise IL-1 and signal through the Type 1 IL-1 receptor (IL-1R1). Although IL-1a is cell associated and IL-1ß is secreted, they have nearly identical biological activity in that they induce adhesion molecule expression on epithelial cells, control fever induction, and play a role in arthritis and septic shock. Signaling activated by the IL-1R1 promotes these activities through a MYD88 signaling pathway similar to those associated with Toll receptors. Recombinant mouse IL-1ß is a non-glycosylated single chain 17,394 Da protein containing 152 amino acid residues.