AQP4 and neuromyelitis optica: There is growing evidence that NMO-IgG/AQP4-IgG is pathogenic in NMOSD [3, 12–15] by a mechanism involving complement-dependent cytotoxicity (CDC) [16, 17] and antibody-dependent cell-mediated cytotoxicity (ADCC) [18, 19], which lead to astrocyte damage and an inflammatory response, causing oligodendrocyte injury, demyelination, and neurological deficits.