Characterization of human liver-specific antigen 1 (HLSA1) defined by the murine monoclonal antibody H2

We developed a murine monoclonal antibody, designated H2, which reacts specifically with human hepatocytes. In the previous study it was demonstrated by immunoperoxidase technique that the reactivity of this H2 monoclonal antibody was restricted to human hepatocytes. We have proposed that the antigen defined by this monoclonal antibody is designated “human liver-specific antigen 1 (HLSA 1)”. We report here the partial characterization of HLSA1. HLSA1 was thought to make a large conglomerate consisting of a unit protein with 15000 dalton molecular weight. HLSA1 was stable at 4°C or 37°C but destroyed by incubation at 60°C for 60min. It was stable at pH 8.0 but destroyed at pH 4.0 and also destroyed by trypsin treatment. HLSA1 was shown to have affinity to some lectins and this result suggest that HLSA1 is a glycoprotein which possesses carbohydrate moieties. Moreover, it was demonstrated by immunoelectron microscopy that HLSA1 was distributed in the perinuclear space, rough endoplasmic reticulum and cell membrane of human hepatocytes. This suggests that HLSA1 is a cell membrane-associated protein.