To investigate whether ADCC bystander killing, as demonstrated in the AQP4-IgG-exposed CHO coculture / NK cell model system, can occur in cell types that are relevant to NMO neuropathology, experiments were done in primary astrocyte-neuron cocultures in which AQP4 is expressed on astrocytes but not on neurons [19, 42]. This evidence concerns the gene AQP4 and neuromyelitis optica.