Fifty-two polyoma-induced primary mouse tumors were tested for transplantability in isologous recipients. Thirty-five tumors grew progressively in the subcutaneous tissue, and several lines have been established in serial transplantation. The remaining tumors did not grow out at all upon transfer.

Eleven among the transplantable tumors have been tested by inoculating known numbers of cells to the following three groups of adult isologous recipients: (a) untreated mice, maintained at a separate, polyoma-free colony, (b) mice preimmunized as adults against polyoma virus containing supernatant fluids from infected mouse embryo tissue cultures, and (c) mice pretreated with heavily irradiated cells of the same tumor. There was a clear and consistent difference between groups a and b for ten of eleven tumors, indicating a state of resistance against transplantation of the established polyoma tumors in the virus-immunized group. With the exception of two out of nine experiments, there was no evidence of resistance in group c, pretreated with irradiated tumor cells. Serum of virus-immunized mice had a certain inhibiting effect on viable polyoma tumor cells upon incubation in vitro with one of four tumors. The possible implications of these findings have been discussed.


This work has been supported by grant C-4747 from the National Cancer Institute, U.S. Public Health Service, and by grants from the Swedish Cancer Society.

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