Antibody-coated sheep erythrocytes suppress the ability of polyclonal B-cell activators to induce plaque-forming cells against sheep erythrocytes

The primary immune response to untreated sheep erythrocytes (SRBC) in vitro was suppressed by the addition of antibody-coated SRBC. A mixture of SRBC and antibody-coated SRBC also suppressed the induction of anti-SRBC plaque-forming cells by the polyclonal B cell activators lipopolysaccharide, purified protein derivative of tuberculin, and native dextran. Injection of a mixture of SRBC and antibody-coated SRBC into mice led to an increased response to SRBC. It seems plausible from the in vitro findings that the Fc part of antibodies complexed to an antigen can exert a negative signal on antigen-specific B cells that cannot be overcome by positive signals delivered by polyclonal B cell activators.