Some properties of normal serum components exhibiting the modulatory effects on the macrophage-mediated hepatocytotoxicity

Abstract

The peritoneal exudate macrophages activated with lipopolysaccharide were shown to inhibit the protein biosynthesis in the isolated hepatocytes by a nonphagocytic mechanism that requires intimate cell contact. These macrophage-mediated hepatocytotoxicity were modulated by serum components. A high molecular weight fraction of senlm(Fr-1)was found to inhibit macrophage hepatocytocidal activity and a modulately low molecular weight fraction of serum(Fr-3)was shown to enhance it. The modulatory activity of Fr-1 component was not affected by treatments with RNase, DNase or neuraminidaae, but this activity was remarkably decreased by trypsin. These were also the cases in Fr-3 modulatory activity. However, heat-stability was somewhat different between active component of Fr-1 and Fr-3. These results suggest that these serum components were protein in nature.