Additive Effects of X-Rays and Methylcholanthrene in Inducing Mouse Leukemia

Publisher Website
Google Scholar
Abstract
34 mice received a total of 1,100 r/air of X-ray (factors 140 kV 2 mm Al filter HVL 4.2 mm Al) in 11 weekly treatments of 100 r as total body irradiation. The mice were 10 wks. of age at the time of the first exposure. 34 mice received 18 skin paintings of methylcholanthrene (0.25% in benzene), the first painting at 14 wks. of age. 48 mice received both treatments (X-ray and methylcholanthrene) at 14 weeks of age and 92 mice served as untreated controls. The 2 leukemogenic agents acted in an additive fashion, when admd. simultaneously, in a stock (dba-212) susceptible to the leukemogenic action of each of these agents. This effect was not apparent in CBA mice, which were susceptible to X-rays but not to methylcholanthrene, These results suggest that susceptibility to each of 2 leukemogens, when used singly, is essential for demonstration of additive effects. The effectiveness of these agents in inducing the disease is dependent on the genetic constitution of the test animal. Longevity of 2 strains of mice was correlated with the length of latent period of induction of leukemia by X-rays.