Efficiency of the first component of complement (C'1) in the hemolytic reaction.

With the use of the first component of guinea pig complement (C'1) labeled in vivo with (14)C-amino acids, we have obtained evidence that, under the conditions required for the assay of C'1, each molecule of C'1 capable of interaction with cell surface antigen-antibody complexes is capable of initiating the reaction sequence that leads to lysis of the cell.