The role of interleukin-8 in inflammation and mechanisms of regulation.

Interleukin-8 (IL-8) is a chemoattractant cytokine produced by a variety of tissue and blood cells. Unlike many other cytokines, it has a distinct target specificity for the neutrophil, with only weak effects on other blood cells. Interleukin-8 attracts and activates neutrophils in inflammatory regions. The importance of neutrophil functions has been recognized in periodontal disease for many years. Neutrophils represent the major population of immigrant cells in periodontitis. In diseases with neutrophil dysfunctions periodontal tissue is lost very rapidly. The response of neutrophils to IL-8 is characterized by migration of the cells, the release of granule enzymes, and other intra- and extracellular changes. Connective tissue constituents are efficiently degraded by neutrophil enzymes, released upon activation. Interleukin-8 is a member of the Interleukin-8 supergene family that includes other small chemotactic peptides with structural homology. It also shares with other cytokines DNA sequence features that suggest common regulatory pathways. In vivo intracutaneous application of IL-8 induces local exudation and a massive, long-lasting accumulation of neutrophils. Though IL-8 plays a role in the cytokine network, its major pathophysiological role lies in affecting neutrophils. This article presents a review of literature on the current knowledge of IL-8, its mechanisms of expression, and the effects it exerts on the neutrophil.