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Biomedical subjects

A M Steffan

Publications and source records attributed to A M Steffan.

At least 37 records · Page 2Linked to original sources
PubMed1990

Permissivity of primary cultures of human Kupffer cells for HIV-1.

Kupffer cells (liver macrophages) represent the largest reservoir of fixed macrophages in the body. Accordingly, we have undertaken a study to evaluate their susceptibility to human immunodeficiency virus type 1 (HIV-1). Five-day-old primary cultures of Kupffer cells (KC) were infected with HIV-1, and as the infection progressed, syncytia appeared. Within the cells, viral proteins were detected by immunofluorescence using monoclonal antibodies directed against gp120 and p24. Electron microscopic examinations revealed the presence of typical Lentivirinae particles. The particles released from KC in the extracellular medium showed reverse transcriptase activity and p24 antigen; they could infect lymphocytic cells and were neutralized by a HIV+ patient's serum or an anti-gp120 monoclonal antibody. Our results thus demonstrate that the interaction of HIV-1 with KC in vitro leads to a productive infection. They suggest that the KC may be involved in the pathogenesis of HIV-1 infection and may (i) participate in the transmission of the infection to the peripheral blood cells, (ii) play a role in the depletion of uninfected CD4+ cells.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Isolation, culture and main characteristics of mouse fat-storing cells: interaction with viruses.

Fat-storing cells were isolated from 15-day-old mouse sinusoidal cell cultures (Kupffer or endothelial cells), where they had multiplied abundantly; they were then purified by a negative selection method based on the fact that they do not possess Fc receptors, as do both other types of cells. The fat-storing cells, which could be subcultured for at least 10 passages, have the main morphological characteristics already described in vivo, in particular, the rough endoplasmic reticulum and the lipid droplets, which become less and less apparent as the number of passages increases. Subcultured fat-storing cells, almost devoid of lipid droplets and vitamin A, were able to take up retinol, as the appearance of a typical autofluorescence indicated; the number of lipid droplets increased concomitantly. Furthermore, the cultured fat-storing cells were able to internalize one-micron-sized latex beads by phagocytosis. Infection of fat-storing cells with mouse hepatitis virus 3, ectromelia or Sindbis virus led to multiplication of the virus particles. There was a direct relation between the multiplication of mouse hepatitis virus 3 in cultured fat-storing cells and the susceptibility of the animals to the virus. In the case of Sindbis virus, interferon is produced, its production being independent of the presence of vitamin A.

Animals↗
PubMed1987

Increased susceptibility of mice to MHV 3 infection induced by hypercholesterolemic diet: impairment of Kupffer cell function.

Nutritionally induced hypercholesterolemia in A/J mice causes susceptibility to Mouse Hepatitis type 3 (MHV 3), whereas normal A/J mice are fully resistant. A/J mice fed with a hypercholesterolemic diet for 15 to 60 days develop 5 to 7 days after MHV 3 infection an acute hepatitis which led to high levels of mortality. A direct relationship was found between the high levels of plasma and hepatic cholesterol and the mortality. In attempting to define the dietary-induced physiological changes which led to the loss of resistance, the Kupffer cells were shown to exhibit an impairment of functions in their ability to become activated by LPS in order to take up C3-coated IgM opsonized sheep red blood cells, C3(IgM)SRBC, or 3H-thymidine Escherichia coli, and the susceptibility to interferon (IFN) for the induction of an antiviral state. Peritoneal macrophages which were studied in comparison with the Kupffer cells showed no impaired functions. The findings presented here indicate an inhibition of host resistance, by nutritional hypercholesterolemia, of A/J mice to MHV 3 infection and that, at least one site of impairment occurs specifically at the stage of Kupffer cells function.

Animals↗
PubMed1986

C3-mediated phagocytosis induced in murine Kupffer cells by "in vitro" activation with endotoxin.

Binding and phagocytosis of red blood cells by Kupffer cells, mediated by C3 receptors, have been studied by incubating sheep red blood cells opsonized with C3, and Kupffer cells isolated from rat and mouse livers. Sheep red blood cell-binding was followed by internalization and phagocytosis only after preincubation of Kupffer cells with bacterial endotoxin. In both species of cells there was a direct relationship between the value of the phagocytic index and the amount of endotoxin needed to stimulate the cells. Increased phagocytosis was related to an increase in the number of phagocytosing cells; it did not depend on an increase in the number of red blood cells internalized per Kupffer cell. C3-mediated phagocytosis, together with the intrinsic and extrinsic antiviral activities, and the synthesis of interferon which take place in activated cells may play an important role in non-specific immunity.

Animals↗
PubMed1985

Inhibition of mouse hepatitis virus type 3 multiplication in activated Kupffer cells.

Mouse Hepatitis Virus type 3 (MHV3) multiplication in isolated murine Kupffer cells was partially inhibited by pretreatment of the cells with lipopolysaccharide (LPS). Supernatants of LPS-treated Kupffer cells contained large amounts of interferon. Inhibition of MHV3 multiplication was also observed when normal Kupffer cells were cultivated in a medium containing supernatants of LPS-treated Kupffer cells. In addition to the antiviral effect of the released interferon, there seems to be another effect of LPS, since Kupffer cells cultured in medium containing anti-interferon alpha beta antibodies were partially activated by LPS to inhibit MHV3 replication. The in vivo consequences of these effects for the local immunity of the liver against MHV3 infection are discussed.

Animals↗
PubMed1984

Kupffer and endothelial liver cell damage renders A/J mice susceptible to mouse hepatitis virus type 3.

Damage to the Kupffer and endothelial cells of the liver sinusoids induced by the administration of sublethal doses of frog virus 3 (FV 3) renders A/J mice which are genetically resistant to mouse hepatitis virus type 3 (MHV 3) highly susceptible to this virus. Liver histopathology of these animals revealed typical necrotic foci containing MHV 3-specific antigens. FV 3-pretreated mice, after MHV 3 infection, showed higher levels of serum transaminase (GPT) than controls, and MHV 3 replicated more rapidly and to higher titres. Our results bear out the important role of the liver sinusoidal lining in protecting against hepatocyte infection and its direct involvement in the resistance of A/J mice to MHV 3 infection.

Animals↗
PubMed1984

Interaction between mouse hepatitis viruses and primary cultures of Kupffer and endothelial liver cells from resistant and susceptible inbred mouse strains.

Infection with mouse hepatitis virus type 3 (MHV 3) of primary cultures of Kupffer and endothelial cells from the livers of resistant (A/J) and susceptible (BALB/c) mice was followed by the appearance of typical syncytia and comparable yields of virus. Using cells from A/J mice there was a delay of about 24 to 36 h in the appearance of the first particles detected by electron microscopy, the maximum viral titre and the number and size of syncytia. The partial resistance to MHV 3 multiplication expressed by cells from A/J mice was also observed when they infected with a strain of low virulence (JHM strain). The delay in MHV multiplication found in the sinusoidal liver cells, mainly in the endothelial cells, may be an important factor in their resistance, by allowing time for the local and systemic responses to clear the infective particles as well as in determining their degree of hepatotropism.

Animals↗
PubMed1983

Membrane lipids of hepatocytes, Kupffer cells and endothelial cells.

The membrane lipid composition of isolated hepatocytes, Kupffer cells and endothelial cells was determined. The hepatocytes are characterized by a lower quantity of gangliosides, cholesterol, sphingomyelin and a reduced cholesterol/phospholipid molar ratio when compared to the two other liver cell types. The main gangliosides of Kupffer and endothelial cells are the GM3 species, and those of hepatocytes are of the polysialogangliosides species.

Animals↗
PubMed1980

[Isolation and culture of human Kupffer cells].

The dissociation of human adult liver parenchyma by collagenase followed by cell separation with centrifugal elutriation allows the Kupffer cells to be isolated. These cells, which may be maintained in culture, retain their main morphological and functional features.

Cell Separation↗
PubMed1979

[Effect of a water-soluble derivative of silymarin on morphological and functional alterations of mouse hepatocytes induced by Frog Virus 3 (author's transl)].

Pretreatment of mice with silymarin dihemisuccinate sodium salt (SHS-Na) 300 mg/kg 24 and 16 h before infection completely protected against the lethal effect of Frog Virus 3 (FV3). After the inoculation of 1 LD100 of virus it could be shown that: a) the same amount of radioactively labelled virus was found in the liver of control and SHS-Na treated animals, b) in SHS-Na pretreated animals the shut-off of macromolecular syntheses in the liver was considerably less extensive, c) the histological changes in the hepatocyte nuclei were attenuated in SHS-Na pretreated animals and the serum titer of the transaminases did no increase, d) in SHS-Na pretreated mice there were only limited functional alterations of the sinusoidal cells as studied by carbon phagocytosis and the serum titer of the lysosomal enzymes was only slightly modified, e) inhibition of protein synthesis during the period of pretreatment with SHS-Na did not decrease the level of protection. These results allow us to conclude that SHS-Na exerts its protective effect on the liver and that sinusoidal cells are most likely involved in this protection.

Animals↗
PubMed1978

Phagocytic properties displayed by mouse hepatocytes after virus induced damage of the sinusoidal lining.

Frog virus 3 (FV 3) inoculated intravenously into mice damages sinusoidal cells and produces a decrease in the carbon uptake capacity of the liver. Histological and ultrastructural examinations have shown that in FV 3 infected animals part of the inoculated carbon is taken up by the hepatocytes and can be located inside cytoplasmic vesicles or dense bodies. The hepatocytes are also able to phagocyte latex particles of 312 nm in diameter. These observations demonstrate that once the Kupffer cells and the endothelial lining are damaged, hepatocytes can display phagocytic properties.

Animals↗