Production of hepatocyte stimulating factor of rat Kupffer cells induced by lipopolysaccharide: partial characterization and effects on alpha 2 macroglobulin gene expression in cultured adult rat hepatocytes

Abstract

Primary cultured rat Kupffer cells stimulated with lipopolysaccharide (LPS) produced a hepatocyte stimulating factor (HSF), which enhanced the synthesis of acute phase protein, alpha 2-macroglobulin (alpha 2M), in adult rat hepatocytes. The Kupffer cell derived-HSF (KC-HSF), enhanced the synthesis of alpha 2M over 100 fold by primary cultured adult rat hepatocytes, in the presence of dexamethasone (Dex). The synthesis of albumin was not stimulated by the factor, even in the presence of Dex. The alpha 2M mRNA increased exponentially starting at 3 hr after addition of the factor. Therefore, the synthesis of alpha 2M stimulated by KC-HSF is probably controlled at the pretranslational phase. The LPS stimulated production of the KC-HSF was inhibited by actinomycin D. The HSF was precipitated between 35% and 65% saturation with ammonium sulfate and collected in the over 30,000 daltons fraction, by molecular sieving. Sephacryl S-200 gel chromatography revealed two distinct forms of HSF with apparent molecular weights of approximately 30,000 and 100,000 daltons. The majority of the activity was recovered in the latter fraction. Isoelectric chromatofocusing of the 100,000 daltons form of HSF yielded a single peak of activity with an apparent isoelectric point (pI) of 4.2. Each fraction contained the interleukin-1 (IL-1) activity, determined by thymocyte proliferation assay. These results show that Kupffer cells produce a cytokine, KC-HSF with IL-1 activity but different properties, as seen on the on Sephacryl S-200 gel filtration and isoelectrofocusing from known mouse or human IL-1.