Abstract
It was previously reported that a neonatal injection of 7,12-dimethylbenz (a) anthracene (DMBA) in mice induces a reduction both of the primary immune response to sheep red blood cells (SRBC) and, later in life, of delayed hypersensitivity. In this study we investigated the secondary immune response to SRBC in Swiss mice injected at birth with 100 μg of DMBA. Groups of DMBA treated and control animals were sacrificed respectively 30, 50, 75, 100, 150 and 200 days after treatment with the carcinogen. They were given a priming i.p. injection of 4 × 108 SRBC in saline 20 days before sacrifice and a booster of SRBC 48 h before killing. The numbers of indirect spleen plaque forming cells and the hemagglutinin titers after reduction with 2-mercaptoethanol were determined at the time of sacrifice. It has been constantly found that animals given carcinogen at birth show a depressed secondary response, regardless of the presence of tumors. The present results fit well with our previously reported observations showing a constantly depressed immune response after neonatal DMBA treatment, and further suggest the existence of a relationship between immunodepression and the high rate of tumors that DMBA induces. The results are also discussed in relation to others studies indicating a direct action of leukemia viruses on undifferentiated B-lymphocytes of marrow origin, in view of the suggested activation of a latent lymphoma virus by DMBA.
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