Mina Lee Vernon

Spontaneous Transformation of Rat Cells After Long-term in Vitro Cultivation and the “switch-on” of a New Complement-fixing Antigen

Summary Rat embryo (RE) cells maintained in tissue culture for long periods developed into tumorigenic lines that exhibited morphological alteration. When tested with broadly reactive anti-MSV rat serum, the spontaneously transformed RE (TRE) cells and tumor cells induced by the TRE cells were positive, however, these cells did not react with guinea pig antiserum which is reactive only with the gs-1 antigen of C-type RNA viruses. While the antigen derived from the TRE line appeared similar to that derived from polyoma transformed RE cell line, it was detected much earlier in the latter cell line. Some characteristics of the new rat cell antigens were described.

Neoplastic Transformation of Rat Embryo Cells Induced in Vitro by Rauscher Leukemia Virus

Summary Neoplastic transformation of rat embryo cells in vitro by Rauscher leukemia virus (RLV) is reported. Rat embryo cells infected initially with RLV have replicated infectious virus and produced complement-fixing (CF) antigen characteristic of the murine leukemia-sarcoma virus complex for more than 18 months. Cells from these cultures underwent neoplastic transformation in vitro and produced tumors when injected into homologous hosts. The tumors were serially transplantable, and subsequent transplants continued to carry the initial RLV and to yield CF antigen. The authors wish to thank Mr. H. C. Turner, National Institutes of Health, for supervising CF tests, and Mrs. Ersell S. Richardson and Mrs. M. H. Joglekar for excellent technical assistance. We are also grateful to Dr. L. Rabstein, Microbiological Associates, Inc., for histological examination of tumors.