Interleukin-1: Biology and clinical applications

Interleukin 1 (IL) is a multi functional cytokine whose biological activities encompass multiple health and disease states. The functional role established for IL-1 involves primarily the host's response to inflammation, and affects nearly all tissues and organ systems. IL-1 exerts many of its regulatory effects via induction of other cytokines and their receptors. The IL-1 gene family maps to chromosome 2 and includes coding regions for IL-1α, IL-1β, and IL-1 receptor antagonist. Two distinct receptor proteins have been identified (IL-1 receptors type I and II), and significant post receptor events mediate the biological activities of IL-1. Antigen stimulated macrophages are the primary producers of IL-1, resulting in the stimulation of the immune response, haematopoiesis and pathogenesis of inflammatory and neoplastic states. Its therapeutic applications can be grouped into two categories: strategies using IL-1 administration to induce its agonist effects and those aimed at inhibiting the expression or activity of this cytokine as a means of decreasing inflammation and tissue injury. We review the biology of IL-1 with emphasis on those aspects relevant to its clinical applications.