FAS and myeloid sarcoma: The relevance of the immunoregulatory function of NK cells in MS is emphasized by studies from the group of Takashi Yamamura, who described a particular peripheral NK phenotype to be characteristic of MS patients in remission, with increased production of the anti-inflammatory cytokine, IL-5 (“NK2” cells), and high expression of CD95 (47), which inhibited the production of IFN-γ by Th1 clones (48).