mC7 retains the ability to participate in the assembly of the TCC. (A) HUVECs grown to confluence in 96-well plates were incubated with the mixture of C5b6, C8, and C9 in the absence or in the presence of polyclonal anti-C7 antibodies (20 μg/mL), or C5b6 and C9 as a negative control. The assembly of mTCC was revealed by mAbs anti-C9 neoantigen. Values are mean (± SD) of triplicate determinations of 3 separate experiments (*P < .05 vs complete cell culture medium). (B) Analysis of SC5b-9 formed by incubating C5b6 with C7-deficient serum (C7D) in the presence of either mC7 or soluble C7. The mixture of C5b6 and C7-deficient serum in the absence of C7 served as control. The formation of the complex was documented by ELISA using goat IgG anti-C5 as a capture reagent and mAb aE11 to reveal exposure of C9 neoantigen. The presence of clusterin or S-protein into the complex was evaluated as above except that mAbs anti-clusterin or anti–S-protein were used as revealing reagents (**P < .01; *P < .05 vs control).