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.

No abstract

M a n y antigens have been found to induce the formation of several molecular classes of antibodies. Under most circumstances, the first antibody to be synthesized in response to antigenic stimulation is a 19S ('yM) globulin, while 7S immunoglobulins (3'G) appear somewhat later. The factors controlling the synthesis of these 2 proteins are poorly understood. The recent report of the selective suppression of "),G-antibodies in rabbits by 6-mercaptopurine (6-MP) suggests that the formation of each of these immunoglobulins is controlled by a separate mechanism (1). Furthermore, 19S antibody synthesis in m a n appears more resistant to 6-MP treatment than 7S antibody formation (2, 3). I n the present paper the effect on 7 M -and "~,G-antibody formation of 6-MP has been further investigated in the primary and secondary response of mice and rabbits. Materials and MethodsAnimals.--White Swiss mice of both sexes weighing 25 to 30 gm and white outbred male or female rabbits weighing 3.5 to 4.5 kg were used.Immunization.--Rat erythrocytes were obtained by cardiac puncture from Wistar albino rats and washed 3 times with buffered (pH 7) saline. Twenty groups of 10 mice were immunized with an intravenous dose of 0.25 ml of a 50 per cent suspension of rat erythrocytes (large dose). Sixteen groups of 10 mice were immunized with an intravenous injection of a 2.5 per cent suspension of rat erythrocytes (small dose). A second injection of the same dose of rat erythrocytes for the appropriate group was given either 2 or 3 weeks later in order to study the anamnestic response. Twelve rabbits were injected intravenously with 1 ml of a 50 per cent saline suspension of human type A erythrocytes washed 3 times. A similar injection was given 20 days later.Administration of 1 was brought into solution in distilled water with the minimal amount of NaOH necessary to dissolve the drug. Eight groups of 10 mice were treated daffy with 50 mg/kg/body weight intraperitoneally for the first 10 days of the immunization. Ten groups of mice were given 150 mg/kg/body weight intraperitoneaUy for 4 days beginning on the day of the second injection. Six rabbits received two 10-day courses of 6-MP (6 mg/kg) beginning on the day of each antigen injection.