AQP4 and myeloid sarcoma: The importance of astrocytes in immune inflammatory disorders is further supported by recent clinical evidence that the majority of patients with neuromyelitis optics, a CNS inflammatory disease with similarities to MS, have autoantibodies to aquaporin-4, a molecule expressed in CNS only on astrocyte foot processes 10, and that the severity of clinical signs in such patients correlates with aquaporin-4-specific antibody titers 11.