Inhibitory effect of carrier and hapten preimmunization on delayed hypersensitivity to the carrier.

The different components of the immune response to hapten-carrier conjugates have been supposed to interact with each other. In order to elucidate the interrelationship between hapten and carrier moieties of the antigen molecule at the cellular level, the homologous carrier alone or the hapten conjugated to an heterologous carrier were injected before immunization with the hapten-carrier conjugate. Delayed hypersensitivity to the carrier could be depressed by pretreatment with the hapten or with the carrier depending on which time interval was chosen to elapse between the two injections. The results could be explained by antigenic competition, occurring at the cellular level, between hapten and carrier moieties of the antigen molecule.