IL17A and myeloid sarcoma: Cerebrospinal fluid (CSF)-infiltrating CD4+ T cells of patients with MS proliferated and secreted interferon- γ (IFN- γ), a characteristic of the Th1 subset, but not IL-17 when challenged with the myelin oligodendrocyte glycoprotein 35–55 (MOG35 − 55) peptide in vitro (16), a proposed candidate CNS determinant in MS (17).