GFAP and neuromyelitis optica: It has also been reported that IL-6 and GFAP are elevated in the CSF of patients who experienced the first NMO attack and their high sensitivities (76.9% and 84.6% respectively) are similar to those of AQP4-IgG in the serum, which suggests that CSF IL-6 and GFAP might be valuable biomarkers of NMO [66].