Selective suppression of delayed hypersensitivity by the induction of immunologic tolerance.

Administration of DNP-BGG to newborn guinea pigs resulted, in more than half of the animals, in the specific suppression of delayed hypersensitivity to DNP-BGG and BGG, as shown after immunization with DNP-BGG in complete Freund's adjuvant. In contrast, all animals formed antibodies to DNP-BGG, whether or not delayed hypersensitivity to this antigen was present. No difference in antibody titers was found between pretreated and control animals. All animals had antibodies reacting specifically to the hapten DNP, and most of them to the carrier protein BGG, whether or not delayed hypersensitivity to the carrier protein was present. Furthermore, some animals with and without positive 24 hr skin test to DNP-BGG had antibodies with a combined hapten-carrier protein specificity to this antigen, i.e., a specificity which is similar to that of delayed hypersensitivity. Thus, delayed hypersensitivity and antibody formation to similar antigenic determinant were differently affected by injection of antigen in the neonatal period. The finding that delayed hypersensitivity and antibody formation could be dissociated by the induction of immunologic tolerance supports the assumption that delayed hypersensitivity and antibody formation are different immune processes which are not necessarily linked together.