On the edge: the physiological and pathophysiological role of chemokines during inflammatory and immunological responses

Most, if not all, chemokines bind to seven transmembrane spanning G protein -coupled receptors and activate cellular migration. Stimulated chemokine ex pression is essential for directing leukocyte emigration from the circulati on into sites of inflammation and tissue damage. In contrast, constitutive chemokine expression plays a role in the development of lymphoid cells, org ans, and tissues. The present review examines rheumatoid arthritis and tran splantation rejection as two examples of pathological conditions where chem okine directed leukocyte infiltration aids in the pathogenesis of the disea se. We further discuss insights into leukocyte trafficking gained by chemok ine and chemokine receptor transgenic and null mutant mice.