Characterization of a mature bile duct antigen expressed on a subpopulation of biliary ductular cells but absent from oval cells

Abstract

Hybridomas were produced with immune spleen cells generated by immunization of Balb/c mice with oval cell antigen (OC.2)-positive 17-day fetal liver cells isolated on antibody-coated magnetic beads. A primary screen by indirect immunofluorescence on frozen sections of fetal and adult liver identified several hybridomas secreting antibodies reactive with bile ducts and oval cells. One of these recognized an epitope, designated BD1, which was expressed on intrahepatic bile ducts in 16-day fetal and adult rat liver and in liver from rats fed a choline-deficient diet containing ethionine and rats treated with 2-acetylaminofluorine, but was absent from morphologically defined oval cells induced by a choline-deficient diet containing ethionine or by 2-acetylaminofluorine. Double-labeling immunofluorescence analysis with monoclonal antibody BD1 and OV6, a monoclonal antibody that reacts uniformly with all bile ducts and oval cells, revealed that BD1 expression on the intrahepatic bile ductular cells of normal adult rat liver was heterogeneous with a major ductal cell population (60% to 70%) expressing high levels of BD1 and a minor ductal cell population (30% to 40%) displaying undetectable or low levels of BD1 expression. Analysis of fetal liver demonstrated the presence of BD1-positive cells at day 16 of gestation on duct-like structures in contact with portal mesenchyme, an observation suggesting that expression of BD1 was associated with commitment of hepatoblasts to a ductular lineage. Taken together, our findings suggest that oval cells may be derived from an antigenically distinct subpopulation of bile ductal cells.

Monoclonal antibody to novel cell surface epitope on Hsc70 promotes morphogenesis of bile ducts in newborn rat liver

“…Animals were fed standard rat chow ad libitum and were housed in an alternating 12-h light/dark cycle environment. Newborn Fisher rats were injected into the spleen at 24-h intervals for three consecutive days with 20 µg of MAb OC.10, MAb OC.5, a control IgM antibody that reacts with the cell surface of cholangiocytes (Hixson et al 2000), or MAb BD.1, an IgM antibody against a cholangiocyte cytoplasmic protein (Yang et al 1993a). Five hours after the third injection, livers were excised and frozen in hexane chilled with a dry ice-acetone bath.…”

“…Rat biliary tree isolated following collagenase perfusion of the liver as described by Yang et al (1993a) was solubilized in 0.5% Triton X-100 with protease inhibitors (Roche Diagnostics Co., Indianapolis, IN, USA) for 2 h at 4°C. Clarified extract was passed over wheat-germ agglutinin coupled to Sepharose at a protein concentration of 5 mg/ml.…”

“…Proteins separated by 7.5% SDS-PAGE were transferred onto nitrocellulose (Trans-Blot Transfer Medium, Bio-Rad Laboratories) and immunoblotted as described (Yang et al 1993a). Reactivity was visualized by chemiluminescence with SuperSignal West Pico chemiluminescent substrate according to the manufacturer's instructions (Pierce Chemical Co.).…”

Development and differentiation of bile ducts in the mammalian liver

“…3, Table 1) . The next step in bile duct differentiation is the expression of CK 19, BD1 antigen, DBA-binding sites, and increased expression of A6 antigen in the fetal rat and mouse liver (Table 1) Carthew et al, 1989;Gall and Bhathal, 1989;Engelhardt et al, 1993;Yang et al, 1993b). CK 7 is expressed in the biliary epithelial cells in the late gestational stage .…”

Phenotypic Heterogeneity within Clonogenic Ductal Cell Populations Isolated from Normal Adult Rat Liver

“…Several of these have been used extensively for delineating lineage relationships during fetal development and carcinogenesis in the adult liver. Most recently, mAb directed against surface antigens on hepatocytes, bile ductal cells, and oval cells have been used successfully in combination with magnetic beads, panning, or fluorescence-activated cell sorting to enrich for antigenically defined subpopulations in fetal (26,32) and normal adult (27) rat livers.…”