RESUMEN
Apolipoprotein E (apoE) is synthesized by a wide variety of cells including cells of the monocyte-macrophage lineage. In order to assess the quantitative significance of apoE synthesis in a mature tissue macrophage, apoE synthesis was compared in Kupffer cells and hepatocytes isolated from rat liver. Immunoreactive apoE synthesized by both cell types exhibited identical isoform patterns when examined by high-resolution two-dimensional gel analysis. ApoE synthesis was not detected in hepatic endothelial cells. Northern blot analysis using a rat apoE cDNA probe demonstrated a single mRNA species of approximately 1200 nucleotides in freshly isolated hepatocytes and Kupffer cells. The absolute content of apoE mRNA in each cell type was determined with a DNA-excess solution hybridization assay. The apoE mRNA content (pg/microgram RNA) for Kupffer cells and hepatocytes was 35.7 and 98.8, respectively. Accounting for cellular RNA content and the population size of each cell type in the liver, Kupffer cells were calculated to contain about 0.7% of liver apoE mRNA; hepatocytes account almost quantitatively for the remainder. These results suggest that Kupffer cells are not major contributors to the plasma apoE pool. After intravenous injection of bacterial endotoxin, apoE mRNA was decreased in freshly isolated Kupffer cells whereas whole liver showed no change in apoE mRNA. Endotoxin treatment had no effect on the apoE mRNA content in several peripheral tissues. These results indicate that apoE expression in vivo is differentially regulated by endotoxin in Kupffer cells as compared to hepatocytes or apoE-producing cells in peripheral tissues.
Asunto(s)
Apolipoproteínas E/biosíntesis , Macrófagos del Hígado/metabolismo , Animales , Apolipoproteínas B/metabolismo , Sondas de ADN , Electroforesis en Gel Bidimensional , Endotoxinas/farmacología , Hígado/citología , Masculino , ARN Mensajero/análisis , Ratas , Ratas EndogámicasRESUMEN
Radioimmunoassay analyses of serum are widely performed to monitor the incidence of hepatitis B virus infection. As an alternative to serum analyses, the authors have explored the feasibility of using gingival crevicular fluid for the detection and quantitation of hepatitis B viral immunologic markers. The results of the study demonstrate that the hepatitis B surface antigen can be easily quantified in gingival fluid. Confirmation of the presence of the hepatitis B e antigen can also be made, but this is more difficult because of the small amounts of gingival fluid currently being assayed. Antibody to the hepatitis B surface antigen can be quantitated in high-titered persons.
Asunto(s)
Anticuerpos Antivirales/análisis , Antígenos Virales/análisis , Líquido del Surco Gingival/inmunología , Gingivitis/inmunología , Virus de la Hepatitis B/inmunología , Sangre , Portador Sano , Hepatitis B/inmunología , Humanos , RadioinmunoensayoRESUMEN
The cellular sources of collagen in normal rat liver have been examined. Hepatocytes and nonparenchymal (sinusoidal) cells were isolated and established in primary monolayer culture. These cells were incubated with radiolabeled proline in the presence of l-ascorbate and beta-aminopropionitrile. Nondialyzable material was prepared from the cell layer and the medium from each type of culture. The level of collagen accumulation was determined by measuring labeled hydroxyproline and sensitivity to purified bacterial collagenase. In hepatocytes, collagen represented 0.2% of both secreted and cell-associated labeled protein. In sinusoidal cells, collagen was 3.2% of secreted and 1.1% of cell-associated proteins. The total secreted labeled collagen, expressed per microgram of DNA, was similar in hepatocytes and sinusoidal cells. However cell-associated collagen in hepatocyte culture was approximately 10-fold that present in sinusoidal cells. These findings indicate that, while collagen formation is a relatively important function of sinusoidal cells, in normal liver the contribution of hepatocytes to total hepatic collagen accumulation may be substantial.