IL15 and neuromyelitis optica: Astrocytic IL-15 is inducible and has a dual role on brain injury in different CNS diseases (17, 18), to assess whether astrocytic IL-15 level was increased in NMO, we compared the expression of IL-15 in astrocytes in the brain tissue from the ipsilateral hemisphere to the contralateral hemisphere or sham control at day 3 after injection of recombinant NMO-IgG (rAb-53) and HC.