AQP4 and neuromyelitis optica: To test the hypothesis that restricted access of serum NMO-IgG to AQP4 in peripheral tissues might account for the absence of NMO pathology in the periphery, and as a first step in generating mouse models of NMO based on peripheral NMO-IgG administration, we determined the cellular distribution and pharmacokinetics of NMO-IgG following peripheral and CNS administration.