AQP4 and neuromyelitis optica: To further substantiate our findings, we repeated these experiments with intrastriatal injection of IL-1β, and intraperitoneal application of IgG from 3 additional anti-AQP4 antibody-positive NMO patients, 2 different anti-AQP4 antibody-negative NMO patients, 3 anti-AQP4 antibody-negative MS patients, and from 2 different AQP4 antibody-positive NMO patients after depletion of AQP4-specific antibodies.