Multiple nature of the third component of guinea-pig complement: I. Separation and characterization of three factors a, b and c, essential for haemolysis*

Three factors essential for the lysis of EAC′₁₄₂ cells are described and designated as a, b and c. These factors exhibit characteristic properties with respect to certain inactivating agents. They can be neatly separated by chemical fractionation. A simple assay method is described for each factor. Preparative methods for two highly reactive intermediate cellular products are given. Evidence is presented suggesting that besides a, b and c at least two additional factors are involved in the lytic action of C′₃.