IL-17A plays an important role in the autoimmune-pathogenesis, since (i) increased numbers of IL-17+ CD4+ and CD8+ T cells are detectable in active as compared to inactive areas of MS lesions15, (ii) genetic risk factors related to IL-23-IL-17 axis associate with MS3,5, (iii) increased IL-17A mRNA levels are detectable in MS52 and (iv) IL-17 contributes to disruption of blood–brain–barrier tight junctions53. Here, CD4 is linked to myeloid sarcoma.