Several authors2,4,7,8 have described a filterable virus capable of inducing tumors in a wide range of hosts (mice, hamsters, rats). Likewise, it has been shown that formation of antibodies is induced by some of these viruses, so that treated animals are protected against inoculation with the live virus3,6,8 Stewart and Eddy8 induced this immunity in hamsters by injecting a mixture of virus culture, culture fluid, and immune serum which had been incubated overnight at 4 C.
Herein we are reporting some experiments in which Sarcoma 180 cells were incubated in rabbit serum and a similar number of cells in guinea pig serum, followed by inoculation into Swiss mice subcutaneously. Nineteen days after the last of 3 such injections, these mice were challenged with a fresh suspension of 440,000 Sarcoma 180 cells.
Materials and Methods
A suspension of Sarcoma 180 cells was prepared by mincing 1 gm. of