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Biomedical subjects

L Fornůsek

Publications and source records attributed to L Fornůsek.

At least 19 recordsLinked to original sources
PubMed1990

Properties of macrophages from high- and low-responder strains of mice. II. The expression of Fc receptors.

Simultaneous expression of Fc receptors was studied on the model of peritoneal macrophages from two inbred strains of mice, A/J and C57BL/10ScSn, so-called high- and low-responders. Sheep red blood cells and/or synthetic polymer microspheres both coated with monoclonal antibodies of different isotypes were used for detection of Fc receptors. It was proved that the majority of macrophages bear more than one type of Fc receptors, moreover, macrophages expressing at least three types of Fc receptors simultaneously were detected. Both mouse strains vary in the presence of different subpopulations of macrophages bearing particular sets of Fc receptors.

Animals↗
PubMed1988

Limitations of transmembrane transport in drug delivery.

The plasma membrane of all living cells controls the flow of substances, energy as well as information, between the internal cell order and surrounding cell disorder. There are three general routes along which substances may cross this barrier; free diffusion, passive and active transport, and endocytic processes. The subject of polymer drugs where biologically inert polymers bear therapeutically active low molecular weight drugs and targeting moiety became a popular issue in last decade. This review is devoted to the question of the interaction of drugs with the plasma membrane and their transport across it. As the polymer-drug conjugates are macromolecular substances, the main emphasis is focused on the problems of phagocytosis and pinocytosis.

Biological Transport↗
PubMed1988

Effects of bilirubin on murine peritoneal and spleen cells.

The effect of bilirubin on murine peritoneal and spleen cells was investigated. Bilirubin was found to have a strong and rapid effect on the expression of various kinds of Fc receptors on peritoneal macrophages. Significant changes were observed 30 min after the infection of bilirubin. The return to normal values was not observed earlier than after 24 h. The effect of bilirubin on Fc receptor expression of splenic macrophages was less pronounced. Expression of Ia antigen on macrophages was not influenced by bilirubin. The changes in percentage of sIg+ and Thy 1.2+ lymphocytes reflect a change in the ratio of T to B cells in the peritoneal cavity, as bilirubin caused 40% increase in numbers of B cells and a similar decrease in numbers of T cells. The percentage of splenic B lymphocytes was not influenced by bilirubin injection; but the ratio of T helper to suppressor cells was altered.

Animals↗
PubMed1987

Polymer microbeads in immunology.

Synthetic polymer microbeads have been studied extensively and the required properties, including monodispersity and size range 0.05-10 microns can best be achieved by radiation polymerization based on methacrylate derivatives. Fluorochrome-conjugated beads can be used for cell surface markers and simultaneously to study phagocytosis. The paper reviews some of these applications. Cell separation techniques are also described. Future possibilities for immunological and cell biology studies are discussed.

Animals↗
PubMed1987

Membrane and functional characterization of lymphoid and macrophage populations of Peyer's patches from adult and aged mice.

Properties of macrophages isolated from Peyer's patches were compared with properties of peritoneal macrophages. We found a very low expression of all types of Fc receptors as well as a low expression of Ia antigens on Peyer's patch macrophages. No substantial changes in the levels of FcR and Ia antigen expression were found during the process of ageing. The investigation of phagocytic activity showed the activated state of Peyer's patch macrophages. Comparing the surface markers of lymphocytes obtained from Peyer's patches of mice of different ages, we found no differences in the numbers of sIg+, Thy-+ or L3T4+ lymphocytes. The numbers of FcR+ and Lyt 2.2+ lymphocytes decreased markedly with age.

Aging↗
PubMed1986

Separation of human lymphoid cells by affinity chromatography and cell surface labelling by hydroxyethyl methacrylate particles using monoclonal antibodies.

The hydroxyalkyl methacrylate gel Separon, Sepharose 6MB and polystyrene dishes with bound antibodies were used for affinity chromatography of cells isolated from human tonsils and peripheral blood. Enrichment of T cells by filtration through anti-human immunoglobulin Separon or Sepharose 6MB columns was comparable to that achieved by "panning" on dishes or by Nylon wool column fractionation. High enrichment of B cells was obtained when cells pretreated with monoclonal anti-T cell antibodies were fractionated on columns or dishes where anti-mouse antibody was bound. Hydroxyethyl methacrylate copolymer microspheres were conjugated with monoclonal antibodies directed against surface markers of human lymphocytes or with anti-mouse immunoglobulin antibodies and used for surface labelling of cells. The results obtained by immunofluorescence were in good correlation with labelling by hydroxyethyl methacrylate immunobeads.

Animals↗
PubMed1986

Co-expression of different types of Fc receptors on murine peritoneal macrophages.

Simultaneous expression of particular immunoglobulin Fc receptors (FcR) was studied on the plasma membranes of murine peritoneal macrophages. This was facilitated by the use of sheep red blood cells (SRBC) and/or synthetic microspheres coated with monoclonal antibodies of different isotypes. It was concluded that a majority of macrophages bear more than one type of FcR; macrophages bearing at least three types of FcR were present in the peritoneal cavity; macrophages bearing Fc mu R did not bind IgE, IgA or IgG; all macrophages bearing Fc alpha R also expressed Fc gamma 2bR, Fc gamma 3R and Fc epsilon R; all macrophages bearing Fc epsilon R also expressed Fc gamma 2bR and Fc alpha R. Except for Fc alpha R, essentially equivalent numbers of FcR-bearing macrophages were detected when antibody-coated SRBC or polymeric microspheres were used. Simultaneous applications of these reagents permitted the most detailed and direct investigations yet performed of multiple FcR expression on individual cells.

Animals↗
PubMed1986

Isolation, characterization and utilization of the fifth component (C5) of porcine complement.

The fifth component (C5) of porcine complement was isolated in immunochemically pure, homogeneous and native form. The isolated component was characterized, it has a molecular weight of 187,000 (under non-reducing conditions) and two non-identical chains of 112,000 and 76,000 under reducing conditions, respectively. The isolated C5 can be used for the detection of the C5b receptors on murine macrophages. Our findings are in good agreement with the results obtained using a rabbit and a human model, which suggests a high conservativeness of C5 during evolution. The described method of isolation of C5 from easily available porcine serum seems to be convenient for C5 receptors studies.

Animals↗
PubMed1986

Polymeric microspheres as diagnostic tools for cell surface marker tracing.

The adequate expression of cell-surface receptors and antigens is an important requirement for the functional ability of living cells. A lot of different methods for cell surface marker tracing have been described; however, most of these techniques have disadvantages limiting their wide-scale utilization in routine laboratory and clinical practice. The most recent technique for these purposes, approaching near the ideal one, is based on the use of synthetic microspheric particles made of polymers which are formed mainly by emulsion or radiation polymerization of a variety of monomers. The resulting spherical particles bear hydroxyl, carboxyl, amino, or other functional groups capable of covalent binding of proteins, dyes, or chemotherapeutic agents. Fluorescent, radioactive or haptenic labels may be introduced already during the polymerization, too. There are three main fields of application of such specific labeled microspheres in cell biology: (1) detection of cell surface markers; (2) studies of phagocytosis mediated via cell surface markers; and (3) cell separation according to cell surface markers. In this review general principles of preparation and applications of polymeric microspheres in cell biology are summarized.

Antigens, Surface↗
PubMed1985

The effect of bilirubin on the Fc receptor expression and phagocytic activity of mouse peritoneal macrophages.

The effect of bilirubin on the phagocytic activity of mouse peritoneal macrophages and on the expression of Fc receptors and receptors for SRBC was studied. Intraperitoneally administered bilirubin influenced the expression of Fc receptors for IgM, IgG2B, IgA and IgE, whereas the expression of other receptors as well as the phagocytic activity of peritoneal macrophages remained unchanged. The possible mechanism of the effect of bilirubin on Fc receptors is discussed.

Animals↗
PubMed1985

The expression of Fc and complement receptors in young, adult and aged mice.

Age-dependent changes in the expression of Fc receptors (FcR) for different isotypes of immunoglobulins and receptors for C3b, C5b and C3bi fragments of complement on the membranes of peritoneal macrophages were studied with mice of different ages. An age-related increase in expression of Fc receptors for IgM, IgE, IgA, IgG2b and IgG3, and a decrease in the expression of Fc receptors for IgG1 was observed. The expression of FcR on macrophages of donors of different ages corresponded with Fc-receptor mediated phagocytosis. The highest number of C3b-binding macrophages was found in aged mice, in contrast to low numbers of C3bi-binding macrophages at this age. The percentage of C5b-binding macrophages was lowest in adult animals. We also observed effective inhibition of binding of the C3b component of complement by preincubation of macrophages with aggregated IgG and vice versa. These observations suggest that fluctuation in expression of Fc but not C receptors may be important to the generalized changes that occur in macrophage function during development and ageing.

Aging↗
PubMed1985

Properties of macrophages from low- and high-responder strains of mice. I. Effect of antigenic stimulation.

In the high-responder A/J mice a lower percentage of peritoneal macrophages express Fc receptors and accordingly phagocytize less intensely via these receptors than the macrophages of the low-IgG-responder C57BL/10ScSn strain. Similarly, the phagocytosis mediated by the receptors for foreign substances tested by CdCO3 microcrystals is lower in the A/J strain. Pinocytic activity was the same in both mouse strains. Intraperitoneal immunization with sheep red blood cells led to a prompt increase in Fc receptor expression and in both phagocytic and pinocytic activities in A/J mice, while in C57BL/10ScSn mice these activities remained unchanged. A similar effect was found when spontaneous and induced rosette formation with sheep red blood cells was studied. The opposite was true when the phagocytic activity of peripheral leucocytes to non-antigenic synthetic microspheres was studied; after immunization with sheep red blood cells a strong increase was observed not in the A/J but C57BL/10ScSn strain. The importance of these results for the regulatory role of macrophages in immune responses in the low- and high-IgG-responder strains of mice is discussed.

Animals↗
PubMed1984

Enhanced phagocytic activity of blood leukocytes in athymic nude mice.

After 30-min incubation, blood leukocytes of adult athymic BALB/c nude mice (nu/nu) have a distinctly higher methacrylate or yeast particle uptake than leukocytes of euthymic nu/+ or +/+ mice. This permanent enhancement is not due to humoral factors, since the percentage of phagocytosing nu/nu leukocytes increases further in nu/+ littermate's plasma. Also, chronic infection or intraperitoneal immunization causes an additional transitory increase of the percentage of phagocytosing leukocytes and numbers of particles ingested; the phagocytic performance of leukocytes of euthymic mice is raised under these conditions by a greater factor. In fetuses enhanced phagocytosis of nu/nu mice is found only in monocytes. The bulk of ingestion of methacrylate particles is mediated by Fc receptors and significantly more receptors for IgG2B, IgG1, and IgG2A are demonstrable on nu/nu neutrophils; ingestion of particles via these receptors is again higher in nu/nu neutrophils, whereas nu/nu monocytes display a higher uptake via Fc(IgG1) receptors.

Animals↗
PubMed1984

Fc receptor--more answers, more questions.

Fc receptors, belonging to the most important surface structures of a number of cells participating in the immune processes, have been intensely studied during the past decade. The present review summarizes the contemporary knowledge of the specificity and heterogeneity of Fc receptors and of factors influencing their expression, and includes some views on their function. In addition, it mentions their relationship to other cell surface structures, expression of Fc receptors during ontogeny of the organism and in certain diseases. Finally, data concerning the isolation and biochemical characterization of the Fc receptor molecule are presented.

Allergy and Immunology↗
PubMed1984

Phagocytic uptake of synthetic particles in blood leukocytes of fetal and newborn athymic nude mice.

Monocytes are the main phagocytic element in the blood of fetal mice; monocytes of athymic nude mouse fetuses (gestation days 17-20) ingest in vitro, in full blood, significantly more synthetic (HEMA) particles than the monocytes of their euthymic littermates. Blood leukocytes of athymic fetuses also bear much higher densities of Fc receptors for IgG2B. The differences in phagocytic uptake in blood leukocytes disappear and the differences in Fc(IgG2B) receptors decrease at postnatal days 2 and 4.

Animals↗
PubMed1984

Opsonic, cytotoxic, precipitating, blocking of bacterial adherence, and other activities of monoclonal IgE antibody compared with IgA and IgM.

Monoclonal IgE anti-TNP antibodies were compared with monoclonal anti-TNP, IgM and IgA isotypes in different biological reactions. The reaginic activity of IgE antibodies demonstrated in passive cutaneous anaphylaxis reactions and degranulation of mast cells was accompanied by a number of activities known to be associated with other isotypes. The occurrence of relatively high numbers of lymphoid cells and macrophages bearing Fc epsilon receptors suggests a possible role of IgE antibodies in host defence mechanisms acting systematically and/or locally on mucosal surfaces.

Animals↗
PubMed1984

Macrophages of athymic nude mice: Fc receptors, C receptors, phagocytic and pinocytic activities.

Expression of Fc receptors (FcR) for IgG1, IgG2A, IgG2B, IgM, IgA and IgE, binding of C3 and C5 complement components and phagocytic and pinocytic activities were determined in peritoneal and omental macrophages of nu/nu, nu/+ and +/+ Balb/c mice. nu/nu mice showed a higher proportion of FcR and complement receptor-bearing peritoneal macrophages along with a significantly higher phagocytic activity of peritoneal macrophages both in vitro and in vivo. Tests of pinocytic activity in these cells and phagocytic activity in omental phagocytes yielded similar results. We conclude that athymic mice compensate their immune defects by a higher phagocytic activity of their professional phagocytes and a higher expression of receptors mediating this process.

Animals↗