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Spontaneous Transformation of Rat Cells After Long-term in Vitro Cultivation and the “switch-on” of a New Complement-fixing Antigen 1

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.