[Effect of IgG on the primary or secondary induced antibody synthesis]

The effect of IgG as a ligand for Fc gamma receptors on the sheep erythrocytes induced synthesis of IgM and IgG antibodies was studied. The IgG preparations used in these experiments had different effects depending on their IgG1 content. The effects on a primary or secondary induced synthesis of antibodies was not comparable. The IgG preparations were effective in monomeric as well as in aggregated form.