In addition to a Th17 phenotype (CD3+CD4+CD161+CCR6+) characterized by IL17 production, and a classical Th1 phenotype (CD3+CD4+CXCR3+) which is associated with production of IFNγ (6, 7), a heterogeneous CD3+ cell population has been shown to be implicated in MS pathogenesis: these cells express phenotypic markers of both Th1 and Th17 cells, but in varying levels and combinations, and also exhibit a mixed profile, characterized by a CCR6+CXCR3+ immunophenotype and concomitant secretion of IL17A and IFNγ (8–11). Here, IL17A is linked to myeloid sarcoma.