CD55 and neuromyelitis optica: Finally, upregulation of CD55 alone does not target other effectors of NMO pathogenesis, such as AQP4-IgG production and levels, antibody-dependent cellular cytotoxicity, the peripheral complement system, and T cell responses, though atorvastatin could be combined with other currently used or investigational NMO therapeutics such as immunosuppressants, plasma exchange, complement inhibitors, and cell-targeted drugs.