Chemokine and chemokine receptor expression in the central nervous system

A decade ago several new cytokines were described that orchestrated the activation and migration of immune cells. These newly described cytokines, of which interleukin-8 (IL-8) was a representative member, defined a novel group of molecules called chemokines (chemotactic cytokines). Chemokines are low molecular weight, 8-12 kDa, basic proteins that have been classified into four distinct families, CXC, CC, C and CX3C, based on the position of their first two conserved cysteine residues. The expression and biological function of chemokines along with their cognate receptors have been well described on various subsets of leukocytes. Only more recently have these molecules been described on various cells within the central nervous system. These pro-inflammatory proteins have been implicated in a variety of diseases within the central nervous system from Multiple Sclerosis to AIDS dementia. While chemokines are likely to enhance the evolution of central nervous system inflammatory disorders they also have other roles in normal brain function and development. This review summarizes the role of chemokines and their receptors in the normal and pathophysiological brain.