Mechanistic studies of how the mAb 1C9 inhibits MAC formation. (A) 1C9 or mouse IgG (mIgG) was preincubated with purified C6 and then mixed with E^shA and 1% C6-depleted sera. After incubation, the inhibition of hemolysis was measured. (B) E^shA were first incubated with 1% C7-depleted sera and then mixed with 1C9 or mIgG, followed by the addition of purified C7 protein. After incubation, the inhibition of hemolysis was measured. Data represent mean ± standard deviation. Representative results from 3 independent experiments. *P < .05 by Student t test.