C-Type Particles in Primary and Transplanted Lung Tumors Induced in BALB/c Mice by Hydrazine Sulfate: Electron Microscopic and Immunodiffusion Studies2
Primary lung tumors induced in BALB/c mice by hydrazine sulfate, transplants of these tumors in newborn and adult syngeneic hosts taken between the first and twenty-fourth transplant generations, and samples of normal tissue from tumor-bearing mice were studied in the electron microscope for the presence of virus particles. Immunodiffusion studies for the presence of type-C, group-specific viral antigens were done on both transplanted tumors and normal tissues of the same mice. The neoplastic cells of the primary and transplanted tumors retained the typical structure of the cell of origin, the type-B alveolar cell. Cylindrical, type-C, and intracisternal A virus particles were observed. Cylindrical particles were seen only in the primary tumors and, characteristically, originated from dark, granular, cystlike areas of the neoplastic cells. C particles budded from the neoplastic cells or in intercellular spaces in 35% of primary tumors, 62.5% of transplanted tumors in newborn mice, and 31% of those transplanted into adults. Intracisternal A particles were seen in the neoplastic cells of 88% of the primary tumors, 25% of the tumors transplanted into newborns, and in 12.5% of those grafted into adults. In 63.6% of the normal lung-tissue samples, only intracisternal A particles were observed. Type-C, group-specific viral antigens were demonstrated by immunodiffusion in the transplanted tumors but not in the normal organs of tumor-bearing mice. These data suggest a possible activation of type-C virus particles in type-B alveolar cells by a chemical carcinogen.