Immunoprevention of x-ray-induced leukemias in the C57BL mouse.

An attempt to prevent irradiation-induced thymic lymphomas in C57BL mice was made by inducing active immunity to endogenous type-C virus with inactivated Rauscher murine leukemia virus (MuLV) or inactivated Gross MuLV or by transferring passive immunity to endogenous type-C virus with goat anti-Gross MuLV IgG. Control groups received the following immunogen or treatment: inactivated simian sarcoma virus, complete Freund's adjuvant, normal goat IgG, and diluent, in both irradiated and nonirradiated C57BL mice Active immunity to the 70,000 molecular weight glycoprotein AKR-gp70 by immunization with Rauscher MuLV and passive immunity to AKR-gp70 by passive transfer of goat anti-Gross-MuLV IgG was measurable throughout some of the latent period of tumor development; in these two groups a significant reduction in tumor incidence was observed, as compared to the other experimental and control groups. Thus, the present findings support the concept of a type-C virus etiology of irradiation-induced leukemias and demonstrate the applicability of immunologic techniques directed against the endogenous type-C virus in the prevention of this disease.