In MS, the involvement of FASL has been largely investigated, but contrasting results have been reported, and it is not clear whether the levels of FASL expression in lymphocytes from MS patients are increased or decreased compared with HD.38, 39 Thus, the differences in frequency of Th subsets reported in previous studies38, 39 may explain the discordant results on FASL expression levels in total lymphocytes from healthy donors and MS patients. This evidence concerns the gene FASLG and myeloid sarcoma.