Third, systemic adoptive transfer of AQP4 specific IgG antibodies engineered from intrathecal clones of NMO patients or NMO-IgG serum fractions from patients but not AQP4-preabsorbed serum IgG were able to induce additional perivascular astrocyte loss in experimental rats that had been pretreated with activated myelin specific CD4+ T cells to induce disrupture of the blood brain barrier that by itself was subclinical or only mildly symptomatic [21], [22], [23]. This evidence concerns the gene CD4 and neuromyelitis optica.