Biological Activities of Aggregated γ-Globulin

Summary Aggregated human γ-globulin (HGG), obtained by heating, agglutinated human and monkey erythrocytes and rabbit platelets, whereas aggregated bovine γ-globulin (BGG) had neither activity. Complement was essential for the hemagglutination and enhanced the agglutination of platelets. Insoluble fraction of the heat-aggregated HGG and bovine serum albumin (BSA)-rabbit anti-BSA precipitates were comparable, on a weight basis, with respect to the abilities to induce the agglutination reactions. Soluble fraction of the aggregated γ-globulin and soluble BSA-anti-BSA complexes had much less hemagglutinating capacities than the insoluble precipitates, and failed to agglutinate rabbit platelets. Divalent cations were required for the agglutination reactions by the aggregated HGG. The reactions were inhibited by phlorizin which suppress the utilization of C′3. Mechanisms involved in the agglutination reactions and in immune adherence were discussed.