CD4 and myeloid sarcoma: The gut and brain axis is now recognized as a key factor in the pathology of multiple neurological disorders, including MS and its experimental model EAE.25 In EAE and MS, CD4+ effector T cells primed in the periphery migrate to the CNS, where they are reactivated by cDCs and other cells to cause myelin destruction.98,99 In addition, recruited T cells secrete cytokines that modulate the activity of CNS-resident immune cells, such as microglia and astrocytes.100–102