The Immunopathology of Chemotactic Cytokines

Abstract

One of the hallmarks of acute and chronic inflammation is the accumulation of blood-born leukocytes to inflamed tissue. The recruitment of specific leukocyte populations to these areas is one of the most fundamental of all mechanisms associated with an inflammatory response. In order for this process to successfully deliver leukocytes to a site of inflammation, a number of specific steps must occur in an absolute faithful manner. This cascade of events is initiated with the binding of the leukocyte to an activated or “inflamed” endothelium via induced expression of various adhesion molecules on both endothelial cells and leukocytes. Interestingly, this initial process usually takes place in the small venules under a large shear stress. Once the leukocyte populations bind to the endothelium, these cells migrate from the vascular space, through the basement membrane matrix, to the area of interstitial inflammation. Recent studies have dramatically increased our knowledge concerning leukocyte extravasation. This is especially true of the research directed at understanding the role of leukocyte-endothelial cell interactions and adhesion molecule expression. In addition, recent advances in understanding leukocyte chemotaxis have revealed a large supergene family of chemotactic polypeptides (1-5). Information gained from studying these novel chemotactic cytokines have generated exciting new concepts regarding the inflammatory response.