References of "Bouzahzah, F"
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See detailLocation and Phenotype of Proliferating T cells in Secondary Lymph Follicles
Hoshi, S.; Bouzahzah, F.; Mancini, I. et al

in Journal of Clinical and Experimental Hematopathology [=JCEH] (2001), 42

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See detailThe influence of follicular dendritic cells on B-cell proliferation depends on the activation of B cells and the mitogen used.
Bosseloir, A.; Bouzahzah, F.; Defrance, T. H. et al

in Scandinavian Journal of Immunology (1996), 43(1), 23-30

Follicular dendritic cells (FDC) are unique non-lymphoid cells found only in lymph follicles. They play a part in the survival, proliferation and differentiation of B cells. To analyse the influence of ... [more ▼]

Follicular dendritic cells (FDC) are unique non-lymphoid cells found only in lymph follicles. They play a part in the survival, proliferation and differentiation of B cells. To analyse the influence of FDC on B-lymphocyte proliferation, we isolated them from human tonsils on albumin gradients and treated them with mitomycin C to prevent the multiplication of lymphoid cells harboured in their cytoplasmic evaginations. FDC cultured for 12-16 h remained attached to the substrate; non-adherent cells were carefully eliminated by washing. Purified B cells cultured alone or with contaminant-cleared FDC were maintained for 2 days in the presence or absence of various stimulants, after which tritiated thymidine uptake by these cells was measured. In the absence of activators, FDC did not induce B-cell multiplication. B cells cultured in the presence of FDC exhibited increased 3H-TdR uptake when activated with anti-CD40 MoAb, anti-immunoglobulin MoAb or transferrin, but not when stimulated with Staphylococcus aureus strain Cowan I (SAC) at a given concentration. In the latter case, B-cell proliferation clearly decreased. In control cocultures where mitomycin-C-treated non-adherent cells were used instead of FDC in the presence of the different stimulants, no increase in B-cell proliferation was observed. The results suggest that, inside the germinal centres, FDC modulation of B-cell proliferation depends on the activation state of the B cells and on the stimulant encountered. [less ▲]

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See detailChemotaxis-Promoting and Adhesion Properties of Human Tonsillar Follicular Dendritic Cell Clusters
Bouzahzah, F.; Antoine, Nadine ULg; Simar, Léon ULg et al

in Research in Immunology (1996), 147(3, Mar-Apr), 165-73

Lymph follicles are globular and compact due to aggregation of lymphoid cells on follicular dendritic cells (FDC). To probe the mechanisms underlying this accumulation of cells, we analyse here the role ... [more ▼]

Lymph follicles are globular and compact due to aggregation of lymphoid cells on follicular dendritic cells (FDC). To probe the mechanisms underlying this accumulation of cells, we analyse here the role played by FDCs in attracting and binding cells. FDCs prepared from human tonsils by mild separation techniques appeared in the form of clusters (FDC clusters), where, via cytoplasmic extensions, they enveloped lymphoid cells. Using Boyden's chambers, we demonstrated that these FDC clusters produced one or more chemoattractants capable of inducing chemotaxis of lymphoid cells. Supernatants of FDC cluster cultures also exerted a chemotaxis-promoting effect. FDC clusters induced true chemotaxis, not merely chemokinesis due to cell activation. They secreted a substance or substances that stuck to the substrate (a cellulose filter) and thus induced haptotaxis. B as well as T cells were attracted, but B cells apparently required the presence of T cells to respond fully to the chemoattractant(s). Subtypes of B cells (IgD+ and IgD-) and T cells (CD4+, CD8+, CD57+ AND CD57-) were tested and all were attracted. Since purified lymphoid cells did not induce these phenomena, FDCs were suspected to do so. FDCs have been shown to establish contact with lymphoid cells. Here we have determined that CD4+ T cells adhere in greater number to FDC clusters than do CD8+ T cells. We thus propose that FDCs specifically contribute to construction of lymph follicles by attracting and determining their cell composition. [less ▲]

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See detailHuman germinal center CD4+CD57+ T cells act differently on B cells than do classical T-helper cells.
Bouzahzah, F.; Bosseloir, A.; Heinen, Ernst ULg et al

in Developmental Immunology (1995), 4(3), 189-97

We have isolated two subtypes of helper T cells from human tonsils: CD4+CD57+ cells, mostly located in the germinal center (GC), and CD4+CD57- cells, distributed through the interfollicular areas but also ... [more ▼]

We have isolated two subtypes of helper T cells from human tonsils: CD4+CD57+ cells, mostly located in the germinal center (GC), and CD4+CD57- cells, distributed through the interfollicular areas but also present in the GC. In a functional study, we have compared the capacities of these T-cell subtypes to stimulate B cells in cocultures. In order to block T-cell proliferation while maintaining their activation level, we pretreated isolated T cells with mitomycin C prior to culture in the presence of B cells and added polyclonal activators such as PHA and Con A, combined or not with IL-2. Contrary to CD4+ CD57- cells, CD4+CD57+ cells did not markedly enhance B-cell proliferation. Even when sIgD.B cells typical of germinal center cells were tested, the CD4+CD57+ cells had no significant effect. This is in accordance with the location of these cells: They mainly occupy the light zones of the GC where few B cells divide. Even when added to preactivated, actively proliferating cells, CD4+CD57 cells failed to modulate B-cell multiplication. On the supernatants of B-cell-T-cell cocultures, we examined by the ELISA technique the effect of T cells on Ig synthesis. Contrary to CD57+ T cells, whose effect was strong, CD57- T cells weakly stimulated Ig synthesis. More IgM than IgG was generally found. Because CD57 antigen is a typical marker of natural killer cells, we tested the cytolytic activity of tonsillar CD4+CD57+ cells on K562 target cells. Unlike NK cells, neither CD4+CD57+ nor CD4+CD57- cells exhibit any cytotoxicity. Thus, germinal center CD4+CD57+ cells are not cytolytic and do not strongly stimulate either B-cell proliferation or Ig secretion. CD4+CD57- cells, however, enhance B-cell proliferation and differentiation, thus acting like the classical helper cells of the T-dependent areas. [less ▲]

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See detailGerminal Center T Cells: Analysis of Their Proliferative Capacity
Bouzahzah, F.; Bosseloir, A.; Heinen, Ernst ULg et al

in Advances in Experimental Medicine and Biology (1995), 378

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See detailModulation of B lymphocyte proliferation inside the germinal center.
Bosseloir, A. L.; Defrance, T.; Bouzahzah, F. et al

in Advances in Experimental Medicine and Biology (1995), 378

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See detailFollicular Dendritic Cells: Origin and Function
Heinen, Ernst ULg; Bosseloir, A.; Bouzahzah, F.

in Current Topics in Microbiology and Immunology (1995), 201

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See detailT cells in contact with follicular dendritic cells
Bouzahzah, F.; Suzuki, S.; Bosseloir, A. et al

in Follicular dendritic cells in normal and pathological conditions (1995)

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See detailB cells in contact with FDC
Bosseloir, A.; Bouzahzah, F.; Simar, L. et al

in Follicular dendritic cells in normal and pathological conditions (1995)

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See detailFDC : origin and function
Heinen, Ernst ULg; Bosseloir, A.; Bouzahzah, F. et al

in Current topics in Microbiology and Immunology (1995)

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See detailUltrastructure of CD57+ cells isolated from human tonsils or blood.
Bouzahzah, F.; Heinen, Ernst ULg; Antoine, Nadine ULg et al

in European Journal of Morphology (1993), 31(1-2), 82-6

The presence of CD4+, CD57+ T cells in the germinal centers has been reported by several authors. The CD57 antigen is also expressed by natural killer (NK) cells. We purified CD57+ cells from human ... [more ▼]

The presence of CD4+, CD57+ T cells in the germinal centers has been reported by several authors. The CD57 antigen is also expressed by natural killer (NK) cells. We purified CD57+ cells from human tonsils and blood by microdissection, rosetting with sheep red blood cells and magnetic cell sorting (MACS) and examined the ultrastructural morphology of these cells. Clear differences were found in cell aspect: blood NK contained large granules which were not found in the tonsillar CD57+ cells. These latter appeared medium-sized and not fully activated. After immunolabeling, the tonsillar CD57+ cells were mainly found in the light zone of the germinal centers. [less ▲]

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