XENOGENIZATION OF TUMOR CELLS BY TRANSFECTION WITH PLASMID CONTAINING env GENE OF FRIEND LEUKEMIA VIRUS

A rat hepatocellular carcinoma cell line (cKDH‐8 cl‐11) showed decreased tumorigenicity after transfection with an envelope gene derived from a Friend leukemia virus (FV‐env gene). FV‐env gene product was found by indirect immunofluorescence staining to be expressed on the cell surface of the FV‐env gene‐transfected cells. The FV‐env‐transfected cells (FV‐env cKDH‐8), however, grew well in X‐irradiated immunosuppressed rats, indicating that the reduction in tumorigenicity of the transfected cells is based on immunological reaction in the host. The rats which rejected FV‐env cKDH‐8 cells showed resistance to rechallenge with the parent cKDH‐8 cl‐11 tumor cells. These results suggest that the FV‐env gene product may elicit antitumor immunity against FV‐env cKDH‐8 cells in a host with a resultant reduction in the tumorigenicity of these cells.