IL17A and myeloid sarcoma: Th17 CD4+ T cells present a proinflammatory secretion pattern different from that of Th1-IFN-γ-producing cells, characterized by the production of IL-17A, IL-17F, granulocyte‒macrophage colony-stimulating factor (GM‒CSF), IL-6, IL-21, IL-22, TNF-γ and the cytolytic enzyme granzyme B.247,248 Importantly, Th17 cells were identified as essential players in the establishment of CNS inflammation in EAE.248 Subsequent studies revealed the expression of IL-17 in the brains of MS patients, specifically in perivascular lymphocytes and glial cells.