AQP4 and neuromyelitis optica: In control studies, these changes were not seen in mice injected with AQP4-IgG alone or control (non-NMO-IgG) IgG and human complement, or in AQP4 knockout mice injected with AQP4-IgG and human complement (data not shown), in agreement with prior studies done using similar mouse models [35, 36].