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Protection of adult mice against tumor challenge by immunization with irradiated adult skin or embryo cells.

Water-soluble mouse embryo antigens, not detectable in normal adult visceral tissues, were found in each of 99 different cancerous tissues in 21 mouse strains (1, 2). Rabbit antiserum against the embryo constituents, absorbed with extracts of adult mouse internal organs, served as the diagnostic reagent in the agar double-diffusion precipitin tests which were employed for detection. Positive reactions were obtained not only with extracts of embryos and all cancers examined, but with extracts of the skin of adult animals as well. Chromatographic estimation of the molecular weights of the antigens from embryos and tumors (65,000 to 70,000) revealed them to be about five times larger than the cross-reacting components in adult skin (10,000 to 15,000). The skin antigens were not detected in embryo viscera or in tumors, even in a sensitive radial immunodiffusion assay with the above antiserum (manuscript in preparation).