Chemokines constitute a family of structurally related polypeptides (MacKay 2001). The chemokines and their receptors exert well-characterized roles in inflammation and physiological function of the immune system, by modulating biological responses, including migration, enzyme secretion, cellular adhesion, cytotoxicity, tumor cell growth, degranulation, and T-cell activation (MacKay 2001; Asensio and Campbell 1999; Gerard and Rollins 2001). Chemokines act through plasma membrane G-protein coupled chemokine receptors on cellular targets (Luster 1998; Rollins 1997). Chemokines and their receptors have been implicated in various pathologies of the human central nervous system (CNS) and have emerged as salient targets for therapeutic intervention (Asensio and Campbell 1999; Glabinski and Ransohoff 1999; Mennicken et al. 1999; Trebst and Ransohoff 2001).