Characterization of L1210 S Cells with Low Sensitivity to Mouse Interferon‐γ

A mouse leukemic cell line L1210 Sg with a low sensitivity to interferon‐γ (IFN‐γ) was described. On the nature of the antiviral action and binding of IFN, L1210 Sg cells were compared with L1210m cell line which is sensitive to IFN‐γ. For a half reduction of the vesicular stomatitis virus‐RNA synthesis, L1210 Sg cells required 500–fold more IFN‐γ than L1210m cells did. However, both cell lines were induced to the antiviral state to the same extent with IFN‐α or ‐β. L1210 Sg and L1210m cells were sensitive to the anti‐proliferative action of IFN‐α and ‐β, but insensitive to IFN‐γ. (2′‐5′)Oligoadenylate synthetase was induced in these cell lines by IFN‐β, but not by IFN‐γ, which suggests that the induction of this synthetase may not be responsible for the antiviral action of IFN‐γ. No substantial difference between L1210 Sg and L1210m cells was found in IFN receptors for IFN‐γ and IFN‐β either in number per cell or in their affinity to corresponding IFN type. However, differences were noted in time course profiles of cell‐associated IFN‐γ at 37 C: in L1210m cells, a rise‐and‐decay profile of IFN‐γ bound to cells was observed at 37 C, but in L1210 Sg cells, rise and slight decay was observed. On the other hand, a similar rise‐and‐decay curve of IFN‐β bound to these cells was observed. These results indicated that the low sensitivity of L1210 Sg cells to IFN‐γ may be due to this slight decay of receptor‐bound IFN‐γ.