CSF2 and myeloid sarcoma: In contrast to viruses, helminthic parasites are known to play a protective role in MS, most likely because (i) they promote tissue repair and (ii) they induce regulatory T and B cells as well as anti-inflammatory cytokines (e.g., interleukin 10 [IL-10] and transforming growth factor β [TGF-β]), which suppress pathogenic autoreactive granulocyte-macrophage colony-stimulating factor (GM-CSF)+ CD4+ T cell responses (reviewed in references 8,  to , 10).