CD27 and neuromyelitis optica: Moreover, Chihara and colleagues described a specific IL-6-dependent B lymphocyte subpopulation in the peripheral blood and CSF of NMO patients: these CD19+ CD27+ CD38+ CD180+ B cells were found to produce AQP4 antibodies and showed enhanced survival as well as AQP4 antibody secretion in the presence of IL-6, whereas blockage of the IL-6 receptor signalling by an anti-IL-6R antibody shortened their survival in vitro [20].