PRODUCTION OF INTERFERON-GAMMA MESSENGER-RNA BY CELLS OF NONIMMUNE ORIGIN

There is general agreement that IFN-gamma is produced only by cells of immune origin (T-cells, NK cells, and recently macrophages). However, indirect evidence has suggested that undetectable, low levels of IFN- gamma produced by cells of non-immune lineage, such as the murine line L-929, enhanced the antiviral activity of IFNs-alpha and/or beta foll owing induction by agents such as the double stranded RNA poly ICLC. S ince L-929 cells were one of the prototypic cell lines for studying mu rine IFN induction and action, we felt that it would be important to v alidate this observation by detection of the mRNA for IFN-gamma. If co nfirmed, it might indicate a role for IFN-gamma in non-immune cells. T he present investigations revealed that mouse L-929 fibroblasts produc e IFN-gamma message following exposure to conventional IFN-alpha/beta inducers such as poly ICLC or Newcastle disease virus. In addition, we found that IFN-gamma itself will induce its own message. We further s how that this is not a phenomenon isolated to transformed cells since we found that normal mouse embryo fibroblasts also produced the messag e, however in a constitutive fashion.