Interleukin-1 (IL-1), a 17-kDa glycoprotein, is one of several important cytokines involved in acute inflammatory responses (1). While IL-1 is produced primarily by monocytes and macrophages, it is also synthesized by astrocytes and microglial cells (1, 2). The IL-1 gene family is comprised of IL-lα,IL-1β, and the IL-1 receptor antagonist (IL-ira) (1, 3). IL-lα and IL-1β represent two unique proteins that are derived from two distinct human genes (1). IL-lβ is the predominant free extracellular form, whereas most IL-lα is membrane-bound. IL-lα and IL-1β are synthesized as precursor molecules, each with an approximate mol wt of 31 kDa. Processing of IL-lα and IL-1β to mature forms of 17 kDa requires specific cellular proteases (i.e., IL-lβ-converting enzyme, [ICE]). The mature forms of IL-lα and IL-lβ share 26% homology at the amino acid level and bind to the same IL-1 receptors (1, 3).
