Effects of subcutaneous administration of chemical carcinogens on leukemia in C58 mice

The effects of sc administration of 3-methylcholanthrene (MCA), 7,12-dimethylbenz[a]anthracene (DMBA), and benzo[a]pyrene (BP) on spontaneous viral leukemia and subcutaneous sarcoma induction have been studied in weanling C58/J mice. MCA produced significantly more sarcomas at the inoculation site than did DMBA or BP; moreover, it interfered with leukemia development. DMBA produced fewer sarcomas, and the incidence of leukemia was comparable to that found in the controls. BP accelerated the incidence of leukemia, although no sarcomas were produced. When the effect of the age of the mice at the time of MCA treatment on the incidence of leukemia and sarcomas was studied, newborn and weanling mice were found to develop primarily sarcomas, whereas no sarcomas were produced in the 16-week-old mice, and 52-64% of the 16-week-old mice developed leukemia. The reason no sarcomas were found in the C58 mice was apparently different from the reason no sarcomas were found in AKR mice, inasmuch as the AKR mice did not live long enough for sarcomas to develop. Immunologic surveillance may have played a part in the sarcoma suppression in the C58 mouse.