The role of chemokines in inflammation.

Chemokines, together with adhesion molecules, cytokines, and proteases, are essential for the directional migration of leukocytes during normal and inflammatory processes. Interleukin-8 and monocyte chemotactic protein-1 are the best-characterized members of the C-X-C and C-C chemokine subfamilies, respectively. However, more than 20 human chemokines have been identified but are only partially characterized at the biological level. Chemokines are involved in chemotaxis of monocytes, lymphocytes, neutrophils, eosinophils, basophils, natural killer cells, dendritic cells, and endothelial cells. This review describes the chemokine subfamilies, the chemokine producer and target cells, their receptors, signal transduction mechanisms, and the role of chemokines during physiological and pathological conditions. More and more evidence points to a role for chemokines in chemotaxis-related phenomena, such as the expression of adhesion molecules, the secretion of proteinases, inhibition of apoptosis, hematopoiesis, and angiogenesis. Chemokines are also involved in diseases such as cancer (tumor regression and tumor metastasis), autoimmune diseases, and bacterial or viral infection.