Regulation of Leukocyte Transmigration: Cell Surface Interactions and Signaling Events

Abstract

A fundamental event in the inflammatory response is recruitment of blood leukocytes to a site of injury or infection, often resulting in tissue dysfunction and damage. The steps in this recruitment process are leukocyte ad- hesion to the endothelial lining of the vessel wall, diapedesis, or transmigration across the endothelial monolayer, followed by directed migration to a site of infection or injury that often in- volves transmigration across epithelia. This review will high- light recent advances in our understanding of the mechanisms of leukocyte-endothelial and leukocyte-epithelial cell adhesive interactions at the level of cell surface protein-protein binding events, and in intracellular signal transduction pathways that regulate leukocyte egress out of the vascular space and into epithelial-lined tissues.