It is hypothesized that in MS and HTLV-1, chemokine and chemokine receptor expression are important mechanisms by which T cells migrate to sites of inflammation. Preliminary evidence supports the roles of several chemokines, including MIP1β, in mediating the enhanced migration capacity of MS derived PBLs. In addition, the ligand CCR-5 seems to be up regulated on PBLs from some MS patients. Analysis of T cell clones does not reveal a definite correlation between cytokine phenotype and chemokine receptor profile. The chemokines and chemokine receptor family are likely to be important molecules in chronic progressive neurological diseases, in which immune cells invade the central nervous system.