Enhancement of antibody production after treatment with actinomycin-D: interrelationships between 7S and 19S antibody.

Administration of actinomycin-D to adult male CF 1 mice immunized with sheep erythrocytes led to enhanced production of haemolytic antibody during the primary response. Haemolytic antibody was shown to be of the 19S variety, while haemagglutinating antibody belonged to the 7S class. The enhancement effect was dependent on the dosage of actinomycin-D and on the relative times of administration of drug and antigen. Increase in 19S antibody production was shown to be associated with and probably dependent on delay and depression of production of 7S antibody, although attempts to reverse the effects of actinomycin-D by passive transfer of 7S antibody were not successful.