Studies on immune hemolysis: preparation of a stable and highly reactive complex of sensitized erythrocytes and the first component of complement (EAC'1): inactivation of cell-fixed C'1 by some complement reagents.

The interaction of sensitized sheep crythrocytes (EA) with guinea pig complement inactivated by treatment with hydrazine or ether has been studied. In both cases EA is converted into EAC'1. The hemolytic reactivity of this complex with respect to a complement reagent that contains C'4, C'2, and C'3 (R1) decays rapidly in the presence of hydrazine-treated complement (R4) or decomplemented guinea pig serum, but not in the presence of ether-treated guinea pig serum or of saline. The rate of decay of EAC'1 is dependent on the temperature, the reaction volume, and the amount of the inactivating reagent. The capacity of R4 and of decomplemented serum to inactivate EAC'1 can be markedly reduced by treatment with ether. The essential conditions for obtaining an optimally reactive EAC'1 consist in exposing EA to ether-treated guinea pig serum in the cold. This procedure yields a highly reactive EAC'1, even when the cells are sensitized with suboptimal amounts of amboceptor.