IFNG and myeloid sarcoma: While IFN-γ- and IL-17-secreting CD4+ T cells are believed to be the pathogenic initiators of MS [31], regulatory T cells (Tregs) fail to suppress the functions of T cells [32], due to both an inherent defect in Tregs—determined by their enhanced apoptosis in MS lesions [33]—and a resistance to Treg suppression by effector T cells [34].