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 expression is essential for directing leukocyte emigration from the circulation into sites of inflammation and tissue damage. In contrast, constitutive chemokine expression plays a role in the development of lymphoid cells, organs, and tissues. The present review examines rheumatoid arthritis and transplantation rejection as two examples of pathological conditions where chemokine directed leukocyte infiltration aids in the pathogenesis of the disease. We further discuss insights into leukocyte trafficking gained by chemokine and chemokine receptor transgenic and null mutant mice.