| Abstract |
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.
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