References of "Heinen, Ernst"
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See detailIsolation of follicular dendritic cells from human tonsils and adenoids. VI. Analysis of prostaglandin secretion.
Heinen, Ernst ULg; Cormann, N.; Braun, M. et al

in Annales de l'Institut Pasteur. Immunologie (1986), 137D(3), 369-82

Follicular dendritic cells (FDC) are able to fix high amounts of immune complexes by C3b or Fc receptors without endocytosis and for long periods of time. In order to determine the function of this ... [more ▼]

Follicular dendritic cells (FDC) are able to fix high amounts of immune complexes by C3b or Fc receptors without endocytosis and for long periods of time. In order to determine the function of this retention, we analysed the secretion of prostaglandin E2 (PGE2) by FDC in vitro; indeed, it is well-known that immune complex fixation on cells may induce PGE2 production. FDC were isolated by enzymic digestion of lymph follicles dissected under the biomicroscope from human tonsils or adenoids. Isolated FDC appeared as spherical clusters where they enveloped lymphoid cells with their cytoplasmic extensions. Tests were performed in synthetic culture media or in media supplemented with foetal calf serum. PGE2 production in FDC suspensions was compared to that of lymphocyte or macrophage-enriched populations prepared from the same human tonsils. In all experimental conditions, FDC and macrophage-enriched cell populations produced high levels of PGE2, inversely to lymphoid cell populations. This secretion was inhibited by indomethacin. At the ultrastructural level, we also showed that 3H-arachidonic acid was metabolized in cell membranes of all three cell types. The PGE2 produced in the culture media, according to our experimental conditions, do not influence cell proliferation, as assessed by 3H-thymidine incorporation tests on phytohaemagglutinin-stimulated lymphocytes. [less ▲]

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See detailTransfer of immune complexes from lymphocytes to follicular dendritic cells.
Heinen, Ernst ULg; Braun, M.; Coulie, P. G. et al

in European Journal of Immunology (1986), 16(2), 167-72

Antigens in the form of immune complexes are retained on the membranes of follicular dendritic cells (FDC) for long periods of time. To examine how immune complexes reach germinal centers, where FDC are ... [more ▼]

Antigens in the form of immune complexes are retained on the membranes of follicular dendritic cells (FDC) for long periods of time. To examine how immune complexes reach germinal centers, where FDC are located, we injected mice with anti-2,4-dinitrophenyl (DNP) antibodies complexed to DNP-myoglobin-coated gold particles. The distribution of the particles in spleens or draining lymph nodes was then determined with the electron microscope. The vast majority of the particles were cell bound. Shortly after injection they were phagocytized by macrophages or fixed on lymphocytes. The latter were found even in the corona of lymph follicles but not in germinal centers. Already 30 min after injection, FDC in contact with the corona were faintly positive but were negative in the center. FDC precursor cells were occasionally observed but in too small a number to account for the transport of immune complexes to the germinal centers. Twenty-four hours after injection colloidal gold particles were found in phagolysosomes of macrophages or on cytoplasmic extensions of FDC in all parts of the germinal centers. Experiments performed on isolated FDC showed that they are not only able to take up free immune complexes but are also able to adsorb immune complexes from pulsed lymphocytes. These results strengthen the idea that lymphoid cells binding immune complexes by their Fc receptors may transport these complexes inside germinal centers. [less ▲]

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See detailInfluence de la cellule folliculaire dendritique sur la survie des lymphocytes in vitro.
Cormann, N.; Heinen, Ernst ULg; Kinet-Denoel, C. et al

in Comptes Rendus des Séances de la Société de Biologie et de ses Filiales (1986), 180(2), 218-23

To study the role of follicular dendritic cells (FDC) in germinal centers, we tried to keep them alive in vitro by culturing entire lymphoid follicles. Ultrastructural studies of those cultures in ... [more ▼]

To study the role of follicular dendritic cells (FDC) in germinal centers, we tried to keep them alive in vitro by culturing entire lymphoid follicles. Ultrastructural studies of those cultures in different conditions of culture technique, medium and temperature have been made. In any considered conditions living FDC were not found in the cultures after the 7th day. But during that period, only lymphocytes in close contact with the cytoplasmic processes of FDC survived. FDC seem thus to exert a positive action on lymphocyte survival in vitro. Moreover, FDC and lymphocytes appeared associated in situ in clusters similar to those obtained after isolation of FDC (Lilet-Leclercq et al., J. Immunol. Meth., 1984, 59, 235). [less ▲]

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See detailIsolation, characterization and possible functions of follicular dendritic cells from tonsils and adenoids.
Kinet-Denoël, C.; Heinen, Ernst ULg; Simar, L.

in Cell sparation: methods and selected applications (1986)

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See detailMouse lymph node follicular dendritic cells: quantitative analysis and isolation.
Heinen, Ernst ULg; Kinet-Denoel, C.; Radoux, Dominique ULg et al

in Advances in Experimental Medicine and Biology (1985), 186

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See detailRetention of immune complexes by Fc receptors on mouse follicular dendritic cells.
Radoux, D.; Kinet-Denoel, C.; Heinen, Ernst ULg et al

in Scandinavian Journal of Immunology (1985), 21(4), 345-53

Follicular dendritic cells (FDC) are located inside lymph follicles and are mainly characterized by their capacity to retain antigens. We investigated this aspect in mice lymph nodes by using bovine serum ... [more ▼]

Follicular dendritic cells (FDC) are located inside lymph follicles and are mainly characterized by their capacity to retain antigens. We investigated this aspect in mice lymph nodes by using bovine serum albumin (BSA) labelled with 5-nm colloidal gold particles and homologous anti-BSA antibodies bound to 20-nm gold particles. Gold-labelled BSA injected alone in non-immunized mice was only rarely found in FDC cytoplasmic interdigitations. Injected in the form of immune complexes, it was retained by FDC. Antigen-free anti-BSA antibodies injected under similar conditions as immune complexes were always found in draining lymph nodes in the same locations as BSA-anti-BSA immune complexes. F(ab')2 from mouse immunoglobulins linked to colloidal gold particles were very rarely found between the FDC extensions, whereas it was intensely phagocytosed by macrophages. Our study permitted precise ultrastructural localization between FDC cytoplasmic extensions or inside macrophages and other cells of the lymph nodes, but it also pointed out that homologous antibodies linked to colloidal gold particles might be retained by FDC in the absence of antigens. These observations, carried out with colloidal gold, were checked by using 125I-labelled anti-BSA antibodies. Complement activation determinations of gold-labelled antibodies or immune complexes showed that antibodies or immune complexes fixed on colloidal gold particles do not activate the complement. This observation enabled us to conclude that Fc receptors play a significant part in the retention of gold-labelled antibodies or immune complexes by FDC of lymph nodes. [less ▲]

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See detailAntigen/antibody retention by follicular dendritic cells (FDC).
Radoux, D.; Heinen, Ernst ULg; Kinet-Denoel, C. et al

in Advances in Experimental Medicine and Biology (1985), 186

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See detailFollicular dendritic cells isolated from human tonsils.
Kinet-Denoel, C.; Heinen, Ernst ULg; Radoux, D. et al

in Advances in Experimental Medicine and Biology (1985), 186

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See detailIsolation of follicular dendritic cells from human tonsils and adenoids. III. Analysis of their Fc receptors.
Heinen, Ernst ULg; Radoux, D.; Kinet-Denoel, C. et al

in Immunology (1985), 54(4), 777-84

Follicular dendritic cells (FDC), isolated from human tonsils or adenoids, were tested for their capacity to retain monomeric, aggregated or antigen-bound human antibodies in the absence of serum. FDC ... [more ▼]

Follicular dendritic cells (FDC), isolated from human tonsils or adenoids, were tested for their capacity to retain monomeric, aggregated or antigen-bound human antibodies in the absence of serum. FDC retain fluorescein-labelled heat-aggregated human immunoglobulins, but not monomeric ones nor fluorescein-labelled F(ab')2 in monomeric or aggregated form. Ultrastructural observations showed that colloidal gold-labelled monomeric, or antigen-bound, antibodies directed against tetanus toxoid are retained by dendrites and membrane infoldings of FDC but are never located in cytoplasmic vesicles. This retention was inhibited by incubating FDC with unlabelled aggregated or antigen-bound antibodies. When gold-labelled anti-tetanus toxoid antibodies were incubated in the presence of protein-A before the contact with FDC, a strong reduction of their retention occurred. This further suggested the presence of Fc receptors on isolated tonsillar FDC. Endocytosis was not observed in isolated FDC, even after prolonged incubation in presence of labelled immune complexes: their Fc receptors are, thus, not related to a phagocytic activity as they are in macrophages. Simultaneous ultrastructural labelling of Fc and C3b receptors with colloidal gold particles of different sizes did not reveal any clear relations between these two receptors on the surface of FDC. [less ▲]

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See detail5-Nucleotidase activity in isolated follicular dendritic cells.
Heinen, Ernst ULg; Kinet-Denoel, C.; Simar, L. J.

in Immunology Letters (1985), 9(2-3), 75-80

Follicular dendritic cells isolated from mouse lymph nodes were incubated in the presence of AMP to test 5-nucleotidase (5-Nase) activity. Ultrastructural observations showed the presence of 5-Nase on ... [more ▼]

Follicular dendritic cells isolated from mouse lymph nodes were incubated in the presence of AMP to test 5-nucleotidase (5-Nase) activity. Ultrastructural observations showed the presence of 5-Nase on external membranes but also some activity inside the nucleus. 5-Nase was found associated to Fc receptors labelled with homologous immunoglobulins fixed on colloidal gold particles. Lymphocytes and macrophages, found in association with the follicular dendritic cells, were either 5-Nase positive or negative. The hypothetical roles played by 5-Nase in germinal centers are discussed. [less ▲]

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See detailPrecise localization of antigens on follicular dendritic cells.
Radoux, D.; Heinen, Ernst ULg; Kinet-Denoel, C. et al

in Cell & Tissue Research (1984), 235(2), 267-74

Horse-spleen ferritin or bovine serum albumin conjugated to colloidal gold (BSA-gold) were injected subcutaneously in preimmunized mice. In draining lymph nodes both antigens were located in macrophages ... [more ▼]

Horse-spleen ferritin or bovine serum albumin conjugated to colloidal gold (BSA-gold) were injected subcutaneously in preimmunized mice. In draining lymph nodes both antigens were located in macrophages or between the cytoplasmic processes of follicular dendritic cells (FDC). Some of the antigens remained trapped on FDC until day 31 after injection. Simultaneous injection of both antigens showed that they were located between the infoldings of the same FDC. These cells are thus able to retain at least two different antigens on their surface. The peculiar arrangement of ferritin between the cytoplasmic infoldings suggests that this antigen is fixed on both cell membranes by specific antibodies. The trapped immune complexes could thus stabilize the FDC membrane system. The antigen retention requires the presence of specific antibodies since BSA-gold or ferritin injected without preimmunization were not found between FDC processes. Nonantigenic materials, such as colloidal gold or carbon particles, are not trapped by FDC, except when injected in large amounts. The antigens were trapped on the surface of FDC, however unfrequently in close contact with lymphocytes. FDC might protect lymphocytes against an excess of immune complexes and act as regulators of contacts between lymphocytes and immune complexes. [less ▲]

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See detailIsolation of follicular dendritic cells from human tonsils and adenoids. I. Procedure and morphological characterization.
Lilet, C.; Radoux, D.; Heinen, Ernst ULg et al

in Journal of Immunological Methods (1984), 66(2), 235-44

Follicular dendritic cells have been isolated from human tonsils and adenoids and characterized at the ultrastructural level. Follicles were dissected and digested with different hydrolytic enzymes. The ... [more ▼]

Follicular dendritic cells have been isolated from human tonsils and adenoids and characterized at the ultrastructural level. Follicles were dissected and digested with different hydrolytic enzymes. The cells were separated by sedimentation at unit gravity. By this procedure we obtained follicular dendritic cells enveloping lymphocytes with their cytoplasmic extensions in a way analogous to that described for isolated thymic nurse cells. The ultrastructural features of isolated follicular dendritic cells are similar to those observed in situ. Prolonged enzymatic action caused loss of the enveloped lymphocytes. [less ▲]

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See detailIsolation of follicular dendritic cells from human tonsils and adenoids. II. Immunocytochemical characterization.
Heinen, Ernst ULg; Lilet, Chantal ULg; Mason, D. Y. et al

in European Journal of Immunology (1984), 14(3), 267-73

Follicular dendritic cells (FDC) are specialized cells found only within lymphoid follicles. They bind immune complexes and play a role in the presentation of antigen to follicular B cells and in the ... [more ▼]

Follicular dendritic cells (FDC) are specialized cells found only within lymphoid follicles. They bind immune complexes and play a role in the presentation of antigen to follicular B cells and in the generation of B cell memory. In the present report the isolation of FDC from human tonsils and adenoids is described. These isolated cells have an unusual spherical arrangement and enclose lymphocytes within extensions of their membranes. Their ultrastructural features are similar to those observed in situ. The reactivity of isolated FDC with a number of monoclonal antibodies was analyzed by immunofluorescence and by immunostaining (at the electron microscopic level) with colloidal gold. In keeping with the results of previous investigations on tissue sections IgM, IgG and IgA (but not IgD) can be detected on the surface of isolated FDC, as can C3b receptors and the FDC-associated antigen detected by monoclonal antibody R4/23. The immunoglobulins associated with FDC are mostly embedded in an electron-dense material. The majority of the lymphoid cells enclosed within the membrane extensions of FDC are of B cell type. These results suggest that isolated FDC may be suitable for further in vitro investigation of their role in the humoral immune response. [less ▲]

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See detailNatural infection of Swiss mice by the Mouse Mammary Tumor Virus (MMTV). 2. Studies on the pathway of infection
Hainaut, P.; Vaira, Dolorès ULg; Calberg-Bacq, Claire Michelle et al

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1984), 92(1), 28

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See detailFunctional study of human tonsillar follicular dendritic cells.
Simar, L. J.; Lilet, Chantal ULg; Heinen, Ernst ULg et al

in Acta Oto-Rhino-Laryngologica Belgica (1984), 38(3), 278-87

Follicular dendritic cells (FDC) isolated from human tonsils and adenoids appear as round clusters where the FDC surround lymphoid cells. Using fluorescein and colloidal gold labelled antibodies we ... [more ▼]

Follicular dendritic cells (FDC) isolated from human tonsils and adenoids appear as round clusters where the FDC surround lymphoid cells. Using fluorescein and colloidal gold labelled antibodies we determined their surface antigens, the immunoglobulins they fix and the cells they envelope. Isolated FDC react with specific anti-FDC antibodies but also with an anti-monocyte/macrophage antibody and with anti-HLA-DR antibodies. They retain IgG, IgM, IgA and IgE but not IgD immunoglobulins; this retention occurs, according to our results, via their Fc and C3b receptors. The cells they envelope are mainly B cells, but also occasionally T helper cells. T suppressor cells were only rarely found in contact with FDC. We suggest that FDC create a micro-environment favourable to the proliferation and differentiation of B cells during the humoral response. [less ▲]

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See detailColloidal gold, a useful marker for antigen localization on follicular dendritic cells.
Heinen, Ernst ULg; Radoux, D.; Kinet-Denoel, C. et al

in Journal of Immunological Methods (1983), 59(3), 361-8

Bovine serum albumin (BSA) bound to colloid gold particles (BSA-gold; 20 nm diameter) and injected into preimmunized mice was found at ultrastructural level in different locations of the lymph nodes. It ... [more ▼]

Bovine serum albumin (BSA) bound to colloid gold particles (BSA-gold; 20 nm diameter) and injected into preimmunized mice was found at ultrastructural level in different locations of the lymph nodes. It was detected particularly in the secondary lysosomes of macrophages and between the cytoplasmic processes of the follicular dendritic cells. Between these processes the gold particles were isolated or grouped in clusters; they were in close contact with cell membranes or embedded in dense material. Colloidal gold injected alone was not retained on these cells. The presence of anti-BSA antibodies in the serum was necessary for trapping of BSA-gold particles on follicular dendritic cells. Injections of BSA alone after BSA-gold had been administered to preimmunized mice eliminated most of the BSA-gold from the dendritic processes. BSA-gold is thus trapped in the form of immune complexes which behave characteristically. BSA-gold is thus a suitable marker for antigen localization. Being small and electron dense it permits more precise location than radioactive markers. [less ▲]

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See detailEffects of Cis-Pt loaded liposomes on Ehrlich tumor cells
Gillet, Marie-Claire ULg; Heinen, Ernst ULg; Bassleer R

Conference (1982, April)

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See detailCulture of palatal shelves treated with neuramimidase
Baeckeland, E.; Renard, A. M.; Heinen, Ernst ULg et al

in Verhandlungen der Anatomischen Gesellschaft (1982), 76

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See detailFollicular dendritic cells in lymph nodes after x-irradiation.
Kinet-Denoel, C.; Heinen, Ernst ULg; Radoux, Dominique ULg et al

in International Journal of Radiation Biology and Related Studies in Physics, Chemistry, and Medicine (1982), 42(2), 121-30

Follicular dendritic cells (FDC), non lymphoid cells present in lymph follicles, are characterized by numerous cytoplasmic processes retaining antigen-antibody complexes. Their origin, nature and function ... [more ▼]

Follicular dendritic cells (FDC), non lymphoid cells present in lymph follicles, are characterized by numerous cytoplasmic processes retaining antigen-antibody complexes. Their origin, nature and function are unknown. Mice inguinal lymph nodes after 4.5 or 7.5 Gy X-irradiation were depleted of lymphoid cells. Ultrastructural observations during the first few days post-irradiation show that FDC are unaltered and possess dendritic processes enveloping dense material. Furthermore, they show intense metabolic activity. A lamina densa, never observed so well-developed in other lymph node cells, was detected around the nuclear envelope. The localization of junctions between FDC was analysed. FDC preserve their typical cytoplasmic processes even if lymphoid cells are rare. The latter thus seem not to be responsible for the maintenance of FDC integrity or their development. The possible role of this for antibody production is discussed. Irradiated lymph nodes of lymphoid cells are highly convenient for studying FDC. Isolation of FDC from irradiated lymph organs would seem to be possible. [less ▲]

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