IL6 and neuromyelitis optica: However, no immunosuppressive therapy has been established for either SSM or NMO.[7–9] A recent study reported that the serum and cerebrospinal fluid (CSF) levels of interleukin-6 (IL-6) were elevated in the acute exacerbating period of NMO,[10] indicating that IL-6 is closely involved in the pathophysiology of NMO.