The Fas–FasL pathway in Treg cells obtained from MS patients has never been investigated; however, in another human chronic inflammatory disease, acute coronary syndrome, an alteration in the Fas/FasL pathway in Treg cells was described: here, in fact, Treg but not Th17 cells are sensitive to Fas-mediated apoptosis, and this could determine an imbalance between these two subsets, favoring inflammation (120). Here, FAS is linked to myeloid sarcoma.