AQP4 and neuromyelitis optica: Based upon those results, we hypothesized that C. perfringens may have dual functions in NMO pathogenesis: it may 1) serve as its own proinflammatory adjuvant, promoting Th17 polarization; and 2) expose a determinant of a Clostridium ABC-TP that cross-reacts with AQP4 leading to expansion of AQP4-reactive T cells (see Fig. 4).