Control studies supporting a complement bystander mechanism. a. Effect of C6 depletion. Cocultures were incubated with 20 µg/ml AQP4-IgG and 2% C6-depleted serum, without or with added C6, immunostained for AQP4 and MBP, with dead cells stained red. b. Direct astrocyte injury by α-aminoadipic acid. Cocultures were exposed to 2 mM α-aminoadipic acid for 75 min and processed as in panel a. c. Percentage dead oligodendrocytes at different distances from the center of dead astrocytes (mean ± S.E.M., n=6, * P < 0.01 comparing with control serum for each distance range).