[Common antigens of oval cells and cholangiocytes in the mouse. Their detection by using monoclonal antibodies].

Monoclonal antibodies (MAb) were produced against antigens (Ag) of oval cells isolated from the preneoplastic murine liver. To suppress the immune response to major antigens common with hepatocytes, the principle of anti-idiotype immunization was employed. Characteristics of three MAb reacting selectively with the foci of oval cell proliferation are described. MAb A6 and G7 detected two different antigens (Ag A6 and Ag G7, respectively) common for oval cells and cholangiocytes. Ag A6 was also found in normal parenchyma (in membranes of single hepatocytes adjacent to portal veins), in the preneoplastic liver (in hepatocytes formed de novo) and in some hepatoma cells. Ag G7 was not detected in hepatocytes. MAb E5 stained the matrix in the areas adjacent to oval cells and large bile ducts. All the three Ag were widely distributed in normal tissues of mice. The significance of the detected Ag as markers of murine liver epithelial cell lines and stages of their differentiation is discussed as well as the possible relationship between Ag A6 and Ag of human blood groups.