Specific antibody-mediated effect on the immune response: suppression and augmentation of the primary immune response in mice by different classes of antibodies

The effect of prior administration of two classes of 7S mouse anti-sheep red blood cell (SRBC) antibodies on the primary immune response to SRBC was studied. Mouse γG(1) and γG(2) immunoglobulins were isolated from serum by zone electrophoresis and density gradient isolectric focusing. The immunoglobulins were defined by qualitative and quantitative studies, and their effects on the primary response were determined by administering doses ranging from 0.5 to 0.001 mg of immunoglobulin 2 hours before injection of antigen. Gamma G(1) antibody suppressed the response to SRBC at all concentrations. High doses of γG(2) antibody partially suppressed 19S plaque-forming cells (PFC), but had no significant effect on serum haemagglutinin (HA) levels. Low doses of γG(2) antibody specifically augmented both the 19S PFC and serum HA levels. It is concluded that the specific suppressing and augmenting influences of antibodies on the primary response are a function of class. In addition, it is proposed that γG(1) and γG(2) antibodies can act as specific regulatory elements during the primary response by exerting these two competing biological effects on antibody synthesis