Primary Immune Response in Swiss Mice Injected at Birth with a Single Dose of 7,12-Dymethylbenz [α] anthracene

Effects of a Single Dose of Rabbit Anti-mouse Lymphocyte Serum on Tumors Induced in Mice by 7,12-Dimethylbenz (a) anthracene Given at Birth

The effects of ALS (anti-lymphocyte serum) and NRS (normal rabbit serum) treatments on the development of malignant lymphoma, lung, subcutaneous and skin tumors induced in mice by 7,12-dimethylbenz (a) anthracene (DMBA) are described. Groups of Charles-River mice, injected at birth with a dose of 100 μg of DMBA, received a single injection of ALS or NRS at the same time as DMBA administration or 10, 20, 30, 40 and 50 days after birth. Incidence, latency, histology and spread of the tumors were studied in all groups. It was found that both ALS and NRS increased tumor incidence and shortened their latency period. Malignant lymphomas were the main tumors whose latency was shortened either by ALS or NRS treatment. In addition ALS treatment apparently increased dissemination of DMBA induced lymphoma in bone marrow.

Secondary Immune Response anti Sheep Bed Blood Cells in Swiss Mice Injected at Birth with a Single Dose of 7,12-dimethylbenz (a) anthracene

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.

Bacillus of Calmette and Guérin and 7,12-Dimethylbenz(α)-Anthracene Carcinogenesis in Mice

The effects of single or repeated Bacillus of Calmette and Guérin (BCG) treatment on the onset of tumors induced by the carcinogen 7,12-dimethylbenz (α) anthracene (DMBA) injected at birth into Swiss mice were studied. Multiple doses of BCG, given at regular intervals significantly lowered the incidence of carcinogen-induced tumors. The DMBA–induced lung adenomas did not differ morphologically from the ones that appeared in mice simultaneously treated with both DMBA and BCG.