Transfection of interferon-gamma gene in animal tumors--a model for local cytokine production and tumor immunity.

After retrovirus-mediated interferon (IFN)-gamma gene transfer, tumor cells constitutively produce IFN-gamma and subsequently increase their surface expression of class I major histocompatibility complex antigens. Such cells are useful for evaluating the comprehensive anti-tumor activity of IFN-gamma in vivo in the mouse. When implanted, the IFN-gamma-producing tumor cells usually lose their tumorigenicity due to specific and/or nonspecific immune responses against the tumor which are probably augmented by the tumor-derived IFN-gamma. This specific immunity is mediated by CD8+ effector cells, i.e. cytotoxic T lymphocytes. Other in vivo effects due to IFN-gamma gene transfer vary with different types of tumor. These results imply a promising potential of tumor-cell targeted IFN-gamma gene therapy against cancer.