Inhibition of terminal complement complex formation and cell lysis by monoclonal antibodies

Three monoclonal antibodies (mabs), two against C5 and one against C6, were identified and characterized. They inhibited the generation of the terminal complement complex (TCC) in serum to over 90% as assayed by a sensitive ELISA based on a neoepitope-specific mab, which recognized TCC-integrated C9. The haemolytic function of the TCC was markedly reduced by all three mabs implying that they are directed to epitopes on C5 and C6 which are essential for TCC formation in both the fluid phase and on erythrocyte membranes. Since the generation of C5a was also impaired by these mabs, they may serve as tools in investigations of the sequelae of the generation of C5a and of TCC.