Induction of ifn-y in macrophages by lipopolysaccharide

In this paper we report that macrophages can be stimulated to express detectable levels of IFN-y-speciflc mRNA. Macrophages from lipopolysaccharide (LPSreaponsIve, C3H/OuJ mice are Induced by LPS to Increase steady-state levels of IFN-y-speciflc mRNA, while those from LPS-hyporesponsive C3H/HeJ mice are not. This Interstrain variation la apparently the result of LPS-speclflc signal differences since macrophages derived from both Lpsr and LpsP mouse strains are able to produce comparable levels of IFN-y-speciflc mRNA following stimulation with polyinosinic - polycytidylic acid. The Identity of the cell type responsible for this IFN-y message appears to be the macrophage as IFN-y-apecIfIc mRNA was also detectable following T and natural killer cell depletion, In the LPS-stlmulated RAW 264.7 cell line, and In a homogeneous population of mature macrophages propagated In vitro by stimulation of bone marrow progenitors with recombinant colony stimulating factor-1. Immunofluorescent staining of fixed and permeabillzed LPS-stlmulated macrophages confirmed the presence of Immunoreactlve IFN-y protein. The possible significance of IFN-y production by macrophages la discussed In the context of normal macrophage differentiation as well as the Inflammatory Immune response.