SERPING1 and neuromyelitis optica: Fig. 2B shows concentration-dependent C1-inh inhibition of cytotoxicity in cells incubated with 2% human complement and a recombinant monoclonal NMO-IgG (rAb-53) (left) and sera from two NMO patients and pooled NMO patient sera (right). C1-inh inhibited cytotoxicity in a concentration-dependent manner, with 50% protection at ∼ 2.5–5 μM C1-inh at 2% human complement. Fig. 2C shows C1-inh protection from cytotoxicity in cells incubated with rAb-53 and 2% rat serum.