We have identified a strong connection between the expression of CCR2 on CCR6+/type 17 cells and a pattern of gene and protein expression associated with pathogenicity in immune-mediated disease and host defense against mycobacteria, and have found that CD4+CCR6+CCR2+ T cells express markers of pathogenicity and activation in the CSF of patients with MS. This evidence concerns the gene CCR2 and myeloid sarcoma.