Intercellular communications in lymph follicles

in Dendritic cells in lymphoid tissues (1991)

IL6 and IL4: localization and production in human tonsils

in Lymphatic tissues and in vivo immune responses (1991)

Microenvironments during antigen stimulation

in Molecular biology of B cells developements (1990)

Intercellular Contacts between Germinal Center Cells. Mechanisms of Adhesion between Lymphoid Cells and Follicular Dendritic Cells

in Acta Oto-Rhino-Laryngologica Belgica (1989), 43(4), 297-320

Intercellular connections exist between germinal center cells especially between lymphoid cells and follicular dendritic cells (FDC). Even after isolation, FDC remain associated to lymphocytes and are ... [more ▼]

Intercellular connections exist between germinal center cells especially between lymphoid cells and follicular dendritic cells (FDC). Even after isolation, FDC remain associated to lymphocytes and are able, in a cell suspension, to establish new connections with others. Using human tonsillar cells or mouse lymph node cells we analysed these connections which were shown to be species-specific. Low temperature as well as absence of Ca++ and Mg++ in the culture medium reduced the adherence of fluorochrome-labeled lymphoid cells to FDC. Colchicine treatment did not impair the adherence, whereas cytochalasin B dit it; this was the first observation underlining the importance of microfibrils in FDC. Antibodies directed towards integrin molecules (LFA-1 alpha or beta chain, CD11a and CD18 respectively) reduced the adherence, others (anti-CR3 or anti-gp 150/95, CD11b and c respectively) did not influence it. Antibodies directed against MHC class II exerted no inhibitory action on the lymphoid cell adhesion to FDC. As, at ultrastructural level, gold-labeled immune complexes can be found between FDC and lymphoid cells, we examined the effect on cell adhesion of the addition of immune complexes to the cell suspensions. It only impaired the lymphoid cell adhesion when complement components were present. IgM complexes were then more inhibitory than IgG complexes. When antibodies against Fc IgG receptors (CD16) were added, the adhesion was strongly reduced whereas antibodies to Fc IgE (CD23) receptors had no influence. The antibody DRC1, specifically recognizing an antigen on human FDC reduced the attachment of cells to FDC. This antigen thus seems to play a role in the intercellular contacts; this is the first function ascribed to this FDC specific antigen. [less ▲]

Cytokines produced in lymph follicles.

in Immunology Letters (1989), 22(2), 129-34

The events occurring inside lymph follicles during a germinal center reaction are poorly understood. Using B and T lymphoid cell populations prepared from human tonsillar lymph follicles, and enriched or ... [more ▼]

The events occurring inside lymph follicles during a germinal center reaction are poorly understood. Using B and T lymphoid cell populations prepared from human tonsillar lymph follicles, and enriched or not in macrophages or in follicular dendritic cells, we examined the production of cytokines by these cells in vitro. Interleukin 6 (IL-6) and tumor necrosis factor (TNF) were found in the supernatants of cultures stimulated with phytohemagglutinin or pokeweed mitogen. IL-1 beta was occasionally detected; its secretion apparently depends on the origin of the tonsils, the stimulation, and the cell populations. IFN-gamma and IL-2 were not produced in significant amounts by these lymph follicle cells. IL-4 was only found in very low concentrations in the supernatant of the different cell cultures. The cell populations containing follicular dendritic cells produced more IL-6 and TNF than the others, especially than those composed of only B and T cells. [less ▲]

Follicular dendritic cells act as accessory cells

in Progress in Leukocyte Biology (1988), 7

Isolation of follicular dendritic cells from human tonsils and adenoids. In vitro culture.

in Advances in Experimental Medicine and Biology (1988), 237

Influence of immunoglobulin isotypes and lymphoid cell phenotype on the transfer of immune complexes to follicular dendritic cells.

in Cellular Immunology (1987), 107(1), 99-106

Follicular dendritic cells (FDC) are located only inside lymph follicles and are characterized mainly by their capacity to retain high amounts of immune complexes by their Fc or C3b receptors. In this ... [more ▼]

Follicular dendritic cells (FDC) are located only inside lymph follicles and are characterized mainly by their capacity to retain high amounts of immune complexes by their Fc or C3b receptors. In this work, we examine the influence of immunoglobulin isotypes and the subset of lymphoid cells (B or T) upon the transfer of immune complexes from lymphocytes to FDC. FDC isolated from mice lymph nodes by enzymatic digestion are able to fix, through Fc receptors, gold-labeled immune complexes presented by lymphoid cells. As demonstrated by electron microscopy, this transfer requires the establishment of close contacts between both cell types. Using different cell selection techniques we show that B lymphoid cells take up immune complexes more efficiently than do T lymphoid cells and transfer a larger number of them to FDC. This transfer mechanism is dependent on the immunoglobulin isotype: immune complexes constituted of IgG2a, IgG2b, and IgG1 isotypes are better transferred to FDC than those constituted of IgG3 and IgM. [less ▲]

Effects of cis-diamminedichloroplatinum (II) loaded liposomes on mouse Ehrlich tumor cells.

in European Journal of Cancer & Clinical Oncology (1986), 22(10), 1139-47

Cis-diamminedichloroplatinum II (cisplatin) heavily or lightly loaded (fluid, solid, negatively charged or neutral) liposomes were prepared. Cisplatin release from liposomes was observed only after long ... [more ▼]

Cis-diamminedichloroplatinum II (cisplatin) heavily or lightly loaded (fluid, solid, negatively charged or neutral) liposomes were prepared. Cisplatin release from liposomes was observed only after long dialysis times or after liver lysosomal enzymatic disintegration in solution. Mouse Ehrlich tumor cells (ELT) cultured in vitro were treated with cisplatin, liposomes or cisplatin loaded liposomes, and the effects on the mitotic activity, the DNA content and the ultrastructure were compared. Cisplatin (1-10 micrograms/ml) had an antimitotic activity and modified the DNA content in ELT cells. Ribosome aggregation, perichromatin or interchromatin granule accumulation, and chromatin condensation or some degree of dispersion could be observed. Negatively charged fluid liposomes had an antimitotic activity and modified the DNA content in ELT cells at lower concentrations (0.3 mumoles/ml) than in the case of neutral fluid liposomes (1.5 mumoles/ml). Negatively charged solid liposomes were not toxic at these concentrations. Ultrastructural analysis of ELT cells treated in vitro with negatively charged fluid liposomes revealed their extracellular adsorption and their disintegration in phagolysosomes. A fusion between liposomes and the plasma membrane was not definitely demonstrated. Cisplatin loaded liposomes also had an antimitotic activity and modified the DNA content in ELT cells. These effects were similar to or more pronounced than those induced by free cisplatin. Ultrastructural analysis revealed some kind of electron dense material in phagolysosomes which was never observed after the treatment with free cisplatin or liposomes alone. Effects on nucleic acids were rarely observed. [less ▲]

Retention of immune complexes by murine lymph node or spleen follicular dendritic cells. Role of antibody isotype.

in Scandinavian Journal of Immunology (1986), 24(3), 327-34

Using monoclonal anti-trinitrophenyl (TNP) antibodies complexed to TNP-myoglobin-coated gold particles, we analysed at the ultrastructural level the retention by follicular dendritic cells (FDC) of immune ... [more ▼]

Using monoclonal anti-trinitrophenyl (TNP) antibodies complexed to TNP-myoglobin-coated gold particles, we analysed at the ultrastructural level the retention by follicular dendritic cells (FDC) of immune complexes containing various antibody isotypes. Gold-labelled immune complexes were injected subcutaneously or intravenously into naive mice and, after 24 h, germinal centres of draining lymph nodes or spleen were examined by electron microscopy. FDC generally retained complexes containing IgG2a and IgG2b better than those formed with IgG1 or IgG3. IgM was rarely retained. FDC isolated from lymph nodes or spleens were incubated in vitro with gold-labelled complexes in a serum-free medium. IgG2a and IgG2b complexes were also retained in vitro in large quantities by FDC; IgG1 and IgG3 complexes were retained in smaller quantities or in highly variable quantities compared with IgG2; IgM complexes were rarely seen on FDC. There was no difference between FDC isolated from lymph nodes or from spleen with respect to the Ig isotypes required for Fc-mediated retention of immune complexes. [less ▲]