Complement channels in membranes: inhibition with a monoclonal antibody to a neoantigen of polymerized C9

The channels produced by complement in red cell membranes are heterogeneous, with diameters of approximately 0.5 to approximately 12.0 nm. We investigated the relationship of the components of the membrane attack complex, C5b through C9, to the functional transmembrane channels greater than 3 nm in diameter. Radiolabelled macromolecules were incorporated into resealed red cell membrane ghosts which were then treated with complement. A monoclonal antibody to a neoantigen in polymerized C9 inhibited macromolecule diffusion through the complement channels. There was also inhibition with polyclonal antisera to C9 but not with antisera to any of the other components of the membrane attack complex. The results demonstrate a functional correlation of the larger complement lesions with the previously described poly C9 tubular structures.