CD4 and myeloid sarcoma: Although during the development of neuroinflammation in MS there are CD4+ (Treg) lymphocytes in the CNS, these are found in fewer numbers and the few that do exist have a diminished capacity to control the inflammatory activity of Th-1 and Th-17 lymphocytes (Table 1; Josefowicz et al., 2012; Mcginley et al., 2018).