Immunofluorescent localization of four serum proteinase inhibitors in normal rat liver

Four serum proteinase inhibitors, alpha 1-macroglobulin, alpha 1-proteinase inhibitor, alpha 1-inhibitor3 and alpha 2-acute phase macroglobulin, were localized in rat liver by immunofluorescent techniques. alpha 1-Macroglobulin was observed predominantly in the sinusoids and alpha 1-inhibitor3 in hepatocytes. In contrast, alpha 1-proteinase inhibitor was localized in two sites, sinusoids and parenchymal cells. The fourth inhibitor tested, alpha 2-acute phase macroglobulin, was barely detectable in normal liver. However, some appeared to be present in the extrahepatocyte space.