The presence of Th17 cells and IL-17 in the foci of EAE and MS, as well as an increase in the number of Th17 cells in blood and IL-17 production by activated peripheral blood mononuclear cells (PBMCs) in vitro, was demonstrated in MS patients during relapse compared with MS patients in clinical remission or with healthy subjects [26]. Here, IL17A is linked to myeloid sarcoma.