Regulation of cellular antibody synthesis. Selective suppression by antibody of the immune response induced by a high antigen dose.

Mice immunized with a high dose of sheep red blood cells and 24–48 hours later given specific antiserum produced on the average only 1 per cent of the direct and indirect number of plaque-forming cells (PFC) found in the non-antibody treated controls, whereas animals given a low antigen dose followed by antiserum produced 30 per cent of the number of PFC found in the controls. It is suggested that the low antigen dose preferentially stimulated antigen-sensitive cells having a receptor for the antigen of high affinity, whereas the high antigen dose in addition stimulated cells having lower affinity receptors and that, therefore, the passively transferred antibody would compete more efficiently for the antigen with the antigen-sensitive cells triggered by a high antigen dose than with the higher affinity cells stimulated by a low antigen dose. When antigen and antibody were introduced simultaneously the selective suppression of the immune response to a high antigen dose did not occur. Possible mechanisms for this finding are discussed.