Influence of subclass-specific anti-idiotypic antibodies on the kinetics of the immune response to BCG.

The role of anti-idiotypic subclass-specific antibodies was analysed in the regulation of the immune response to BCG in the guinea-pig. The idiotypes to BCG were separated into subclasses and anti-idiotypes were carried out by immunizing with the purified IgG1 and IgG2 anti-idiotypes. The in vivo T cell response was recorded by tuberculin skin testing, and the in vitro response by lymphocyte stimulation testing with tuberculin. A suppressive effect was detected in cases where the animals were preimmunized with anti-idiotypic IgG2 against anti-BCG IgG1. In the B cell response, the anti-BCG IgG1 and IgG2 subclasses were also quantified by a solid-phase radioimmunoassay. There were 10 times more IgG2 antibodies than IgG1 against BCG in the guinea-pig, and this major idiotypic subclass was suppressed by the IgG2 anti-idiotype raised against anti-BCG IgG2. The minor component anti-BCG IgG1 was slightly stimulated by both IgG2 anti-idiotypes.