Interferon-gamma or BCG restores the responsiveness of mouse lung macrophages to lipopolysaccharide.

While mouse peritoneal macrophages respond well to lipopolysaccharide, lung macrophages were neither activated for tumor cell cytotoxicity nor killed directly by it. The unresponsiveness of lung macrophages was ascribed to lack of expression of lipopolysaccharide-binding sites on the cell surface. It was found that in vitro treatment of lung macrophages with interferon-gamma or in vivo sensitization of them with viable BCG restored the response by expression of the lipopolysaccharide binding sites. The modes of action of interferon-gamma and BCG in expressing the binding sites on mouse lung macrophages are discussed.