[New differentiation markers of mouse liver epithelial cell lines]. / Novye differentsirovochnye markery épitelial'nykh kletochnykh linii pecheni myshi.

We describe two new markers of mouse liver epithelial cells detected by monoclonal antibodies. Immunomorphological localization of antigens was performed using light and electron microscopy. Antigen G7 is a marker of cholangiocytes and oval cells. Antigen A6 is present in cholangiocytes and oval cells; moreover, it is expressed in normal liver in single hepatocytes adjacent to the portal vein, in preneoplastic liver, in newly formed hepatocytes, and in certain hepatocarcinomas. Thus, antigen A6 is a marker of cholangiocytes, oval cells and of certain stages of hepatocyte differentiation. We also detected phenotypic heterogeneity of Gehring cells in terms of antigen A6 content. We have formulated problem of the relationship between A6-negative Gehring cells and liver stem cells. Both marker antigens are species-specific but are not specific for the liver. Antigen A6 is simultaneously a differentiation marker of cells belonging to the erythroid series. It is expressed in erythroblasts of fetal liver and is absent in erythroblasts of the yolk sac and erythrocytes. The relationship between antigen A6 and blood group antigens is discussed.

[Common antigens of oval cells and cholangiocytes in the mouse. Their detection by using monoclonal antibodies]. / Obshchie antigeny oval'nykh kletok i kholangiotsitov myshi. Vyiavlenie s pomoshch'iu monoklonal'nykh antitel.

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.

[Determination of monoclonal antibody specificity by mixed precipitation ingel]. / Opredelenie spetsifichnosti monoklonal'nykh antitel metodom smeshannoi pretsipitatsii v gele.

The enzyme-immunodiffusion technique is advanced which permits testing monoclonal antibodies included in the precipitate line formed in gel by polyclonal antibodies with the corresponding antigen. Rat or mouse monoclonal antibodies were mixed with polyclonal rabbit antiserum to the antigen at issue. The precipitate formed by immunogen and rabbit polyclonal antibodies included monoclonals.

[Monoclonal antibodies to mouse alpha-fetoprotein]. / Monoklonal'nye antitela k al'fa-fetoproteinu myshi.

Splenocytes of rats immunized with mouse alpha-fetoprotein (MAFP) and cells of mouse myeloma NS-I were used to obtain hybridomas that synthesize antibodies to MAFP (anti-MAFP). Antibody activity was determined by the two tests: solid-phase ELISA and indirect immunoperoxidase staining of the regenerating liver sections of mice poisoned with CCl4. After recloning of one of the hybridomas a clone that effectively synthesized anti-MAFP was selected and reproduced. Anti-MAFP were isolated from cultural fluid of the clone by sorption-elution on CnBr-activated sepharose 4B conjugated with purified MAFP. Monoclonal origin of anti-MAFP has been demonstrated by electrophoretic homogeneity of the preparation, and by its appurtenance to one of the subclasses of rat IgG. Anti-MAFP does not precipitate MAFP but distinctly inhibits the formation of the precipitation line by MAFP and rabbit antibodies to MAFP in the zone of diffusion of monoclonal antibodies. Monoclonal anti-MAFP were high-effective in the reaction with MAFP in both tests. Anti-MAFP specificity is directed to one of the MAFP determinants that is common to rat and human alpha-fetoprotein.

[Macrophage migration inhibition by T-cells in rats after overcoming natural tolerance to alpha fetoprotein]. / Podavlenie migratsii makrofagov T-kletkami pri preodolenii estestvennoi tolerantnosti k alfa-fetoproteinu u krys.

Cellular immunity to alpha-fetoprein (AFP) was studied in rats by the macrophage migration inhibition (MMI) test after breakage of tolerance to homologous AFP of rat (RAFP). A single injection of cross-reacting AFP of mouse (MAFP) has induced the capacity of peritoneal exudate cells of rats to react in the MMI test to both MAFP and RAFP. The second injection of MAFP results in reduction of the MMI reaction to both antigens and the appearance of stimulation in the macrophage migration together with further elevation of antibody titer to MAFP and RAFP. The fractionation of rat peritoneal cells has shown the T-cell nature of MMI reaction to both MAFP and RAFP.