ABSTRACT
Chemokines are a family of structurally related peptides of 8–10 kDaltons that regulate inflammation through cell surface G-protein-coupled receptors on leukocytes. These peptides mediate diverse biological and biochemical activities in leukocytes, including adhesion to endothelium, directed migration, and activation of cytotoxic activities. Initially, chemoattractive products of lymphocyte transformation were termed lymphocyte-derived chemotactic factors, lymphocyte-derived chemotactic factors. Chemokines have been classified into four families, C, CC, CXC, and CX3C, based on the number and positions of the N-terminal-conserved cysteine residues. Since the identification of IL-8 nearly 12 years ago, over 40 chemokines have been identified. Chemokines bind to and activate seven transmembrane G-protein-coupled receptors. All chemoattractant receptors expressed in leukocytes mediate signaling through a heterotimeric G-protein composed of a, ß, and ? subunits. Upon receptor activation, G-proteins dissociate into Ga and Gßγ to activate effectors such as phospholipase C. Chemokine receptors couple to Gi family of G-protein which are pertussis toxin sensitive.
