title: Number of hits necessary for complement-mediated hemolysis.
abstract: The number of hits necessary for the C8 and C9 steps of immune hemolysis was reexamined with a previously unemployed experimental design, in which various numbers of EAC1-7, excess of the supplementary component and a constant amount of the component tested were incubated in a constant volume (Inoue et al. 1976. Infect. Immun. 13: 337). Our results were consistent with previous findings; the steps of guinea pig C8 and C9, the human C8 each followed a one-hit mechanism, while that of human C9 showed ka multi-hit response. When lysis of sensitized erythrocytes (EA) by normal human serum was analysed in a similar way, one-hit curves were obtained. This result, taken together with the above results, suggests that immune hemolysis occurs by a single lesion including a single C8 and multiple C9 in the case of human complement and that normal human serum contains sufficient excess of C9. On the other hand, when C9-deficient human serum was used for lysis of EA, multiple-hit curves were obtained. The mechanism of lysis by C5b-8 may differ from that by C5b-9.
mesh_terms: D000818:Animals; D003185:Complement C8 / Q000502:physiology*; D003186:Complement C9 / Q000502:physiology*; D006168:Guinea Pigs; D006461:Hemolysis; D006801:Humans; D007122:Immunoelectrophoresis
chemical_list: D003185:Complement C8; D003186:Complement C9