Viral and Chemical Leukemia in the Rat: Comparative Study

Summary

In view of the variety of clinicopathologic types of human leukemia, a comparative study of different types of experimental leukemia in the same host appeared desirable. Two types of leukemia can be induced in rats of the same strain by use of viral and chemical carcinogenic agents. Gross virus-induced leukemia is of lymphoid type and is strictly dependent on the age of the recipient and on the amount of virus administered. The thymus is a major factor in conditioning leukemogenesis and being its principal localization. 7,12-Dimethylbenz[a]anthracene (DMBA)-induced leukemia is of myeloid type and is unrelated to either the thymus or the age of the recipient. It requires repeated administration of the drug, is localized in the liver, is not prevented by splenectomy, and appears to be virus-free. These two types of leukemia were studied with the light and electron microscope, cell-free filtrates, immunofluorescence, and serial transplantation. Permanent cultures of Gross virus- and DMBA-induced leukemias, including chloromas, were also established. This comparative study provides an opportunity to consider alternate mechanisms for the process of leukemogenesis.