Tumorlytic activity of autochthonous blood fractions upon spontaneous murine mammary carcinomas

Autologous blood fractions of mice bearing spontaneous mammary carcinoma were assessed for their autotumorlytic capability. In the 180 animals evaluated, it appears that in the blood of these tumor animals there coexists at least two types of biological antagonists ie, one which is capable of inducing tumor breakdown and necrosis and the other which apparently nullifies this action. These results seem additive to the growing body of evidence that the tumorous host has the capability of destroying its own neoplasm but some negative homeostatic mechanism seems to favor the tumor rather than the host.