| Abstract: | Cotransformation with a plasmid containing a thymidine kinase gene (pTK2) and a plasmid encoding human IFN-gamma (pTG11) has been used to establish murine L cell lines expressing human IFN-gamma. The HuIFN-gamma gene was present in 30% of the tk+ cell lines and some of these secreted low levels of IFN into the culture medium. Two of the clones obtained after transformation were selected for detailed analysis. Clone 1-12 constitutively secreted very low levels of HuIFN-gamma in the culture medium. This antiviral activity was characterized by its species specificity and antigenicity as authentic human IFN-gamma In contrast, clone 3-47 produced a HuIFN-gamma activity which could only be detected intracellularly. This clone was resistant to infection both by Vesicular stomatitis (VSV) and Mengo viruses and contained increased levels of enzymes known to be induced by interferon. Our results suggest that clone 3-47 produces a non-secreted HuIFN-gamma like molecule which is able to trigger an antiviral state in the murine cell independent of the interaction with a specific IFN-gamma surface receptor. |
