IL17A and nervous system disorder: Two studies reported that CCR2+CCR5+T cells, which were specifically involved in the development of MS but not in other noninflammatory neurologic diseases, produced a large quantity of IFN-γ and a small amount of IL-17, while CCR2+CCR5− T cells produced a large quantity of IL-17 and a small amount of IFN-γ [36, 63].