The Effect of Chemical and Physical Treatments of Sera on the Hemolytic Activities and Fixation of Complement Nitrogen by Antigen-Antibody Precipitates

Abstract

Little relationship was found between the amount of complement N contributed to specific precipitates and either the hemolytic activity of sera or the components of complement present. The complement component probably responsible for the contribution of complement N to immune precipitates was confirmed to be C′1. Versene and cation exchange resin either decreased or inhibited the contribution of complement N to immune precipitates by guinea pig and human sera. However, these agents had little effect on either the contribution of complement N to immune precipitates or the precipitation of soluble antigen-antibody complexes by rabbit serum. It was found that urea reversibly inactivated the components of complement. The hemolytic activity and contribution of complement N were either completely or partially inhibited. Almost complete restoration of complement activity of the sera occurred after removal of the urea by dialysis.