Ultrastructural location of human hepatocyte growth factor in human liver

Human hepatocyte growth factor has been purified from the plasma of patients with fulminant liver failure, but where this factor is produced in organs or cells of subjects with liver diseases is unknown. Therefore, we used a monoclonal antibody to human hepatocyte growth factor to stain cells in three normal and 29 diseased liver tissues by immunohistochemical techniques. By light microscopy, the immunostained cells seemed to be polymorphonuclear leukocytes because of their segmented nuclei. Some biliary epithelial cells also were stained. Electron microscopy confirmed that the immunostained cells with segmented nuclei were polymorphonuclear leukocytes and that the stained grains were on the membranes of rough endoplasmic reticulum, around specific or azurophilic granules and in the cell sap. Stained grains in the biliary epithelial cells were found sporadically on the inside and outside of the membranes of rough endoplasmic reticulum near the nuclei. Human hepatocyte growth factor is now known to be the same protein as scatter factor and tumor cytotoxic factor, both of which are produced by human fibroblasts in culture, but our results suggest that polymorphonuclear leukocytes in diseased livers are one cellular source of circulating human hepatocyte growth factor. The immunostaining properties of biliary epithelial cells in diseased livers also suggest that the cells produce and secrete human hepatocyte growth factor.