Susceptibility of Newborn Germ-free Mice to Tumor Induction by 3-methylcholanthrene.

A single subcutaneous injection of 0.1 or 0.3 mg. of 3-methylcholanthrene in olive oil was administered to newborn germ-free mice and to mice derived from the germfree colony but reared under conventional conditions (CVN mice). The germ-free mice have no demonstrable infection with bacteria or fungi and no demonstrable antibodies to certain viruses commonly found in laboratory mice. There was little indication from the data obtained in this experiment that suscepti bility to tumor induction by 3-MC was decreased by the absence of demonstrable infection with bacteria or by the apparent absence of certain murine viruses. In general, germ-free mice showed about the same susceptibility to induction of pulmonary tumors and subcutaneous sarcomas as did their conventional controls. Furthermore, leukemia was induced in a few of the germ-free animals but in none of the conventional mice. Females (germ-free and CVN) tended to be somewhat more susceptible than males to pulmonary tumor induction. This was demonstrable only at the lower dose level of 3-MC (0.1 mg.).