Antigen-Induced Suppression of Antibody Synthesis during an in Vitro Secondary Response

The production of antibodies in cell cultures from the draining lymph nodes of rabbits injected in the foot pads with two to four different protein antigens was studied. Antibodies against all of the immunizing antigens were produced simultaneously when aliquots of the cells were cultured 4 to 8 weeks after immunization in the absence of further antigen exposure. In vitro exposure to a single immunizing antigen always resulted in an anamnestic response to the added antigen and a general enhancement of antibody production against cross-reactive determinants on other immunizing antigens. However, antibody production against unrelated immunizing antigens was always significantly suppressed by this exposure. This suppression was not the result of antibody feedback and could not be induced unless the unrelated antigen had been used as a priming antigen.