Given that IL-17-secreting CD4+ T cells have been reported at relatively low frequencies in the blood and CSF, even in MS (Brucklacher-Waldert et al., 2009, Durelli et al., 2009), we therefore examined the expression of both IL-17A and IFNγ in relation to the expression of CCR6. The gene discussed is CCR6; the disease is myeloid sarcoma.