Differential Expression of Cellular Prion Protein on Human Blood and Tonsil Lymphocytes

in Haematologica (2000), 85(5), 475-80

BACKGROUND AND OBJECTIVE: The expression of cellular prion protein (PrPc) on the surface of peripheral lymphocytes has been previously reported, but little is known about its expression on lymphoid cells ... [more ▼]

BACKGROUND AND OBJECTIVE: The expression of cellular prion protein (PrPc) on the surface of peripheral lymphocytes has been previously reported, but little is known about its expression on lymphoid cells from secondary lymph organs. In this report, we compare the surface expression of PrPc on human blood lymphocytes and tonsil lymphocytes. DESIGN AND METHODS: This analysis was performed by cytometry on live lymphocytes isolated from healthy donors or from the tonsils of adults or children. RESULTS: Human peripheral lymphocytes and tonsillar lymphoid cells, but not erythrocytes or granulocytes, express PrPc at their surfaces. Interestingly, we found significantly less PrPc on freshly isolated tonsil lymphocytes, both B and T, than on blood cells. Although tonsil cells bear less PrPc than circulating blood lymphocytes, they are able to express high quantities of PrPc on their surface when placed in culture. However, contrary to previous results, mitogen stimulation does not affect this expression on B- or T-cells. INTERPRETATION AND CONCLUSIONS: We suggest that the PrPc expression by lymphocytes may be modified by interactions occurring during intratissular migration or during cell-to-cell contacts. Whether PrPc plays a role in intracellular communication at this location, as it does in the nervous system, remains an open question. [less ▲]

Detection of Bone Sialoprotein in Human Breast Cancer Tissue and Cell Lines at Both Protein and Messenger Ribonucleic Acid Levels

in Laboratory Investigation : Journal of Technical Methods & Pathology (1996), 75(2), 203-10

The recent demonstration that bone sialoprotein (BSP) can be detected in human breast cancer tissue by immunoperoxidase suggests that this phosphoprotein is ectopically expressed by malignant mammary ... [more ▼]

The recent demonstration that bone sialoprotein (BSP) can be detected in human breast cancer tissue by immunoperoxidase suggests that this phosphoprotein is ectopically expressed by malignant mammary epithelial cells. Its detection in human breast cancer cells raises questions about its potential role(s) during breast cancer progression. Because BSP is secreted and is present in the serum, the positivity of breast cancer cells for BSP could have been the result of an uptake of the circulating phosphoprotein by the cells rather than of an intrinsic expression. We examined the expression of BSP at both the protein and mRNA levels in nine human breast cancer samples as well as in three human breast cancer cell lines (MCF-7, T47-D, and MDA-MB-231) using immunohistochemistry, flow cytometric analysis, immunoblot, and reverse-transcriptase PCR. BSP was detected at both protein and mRNA levels in human breast cancer tissue and in the three human breast cancer cell lines. Using a specific polyclonal anti-BSP antibody, we showed by both fluorescence-activated cell sorter analysis and immunohistochemistry experiments that all of the human breast cancer cell lines studied express BSP. This was localized at the cell surface and in the cytosol of the estrogen receptor-positive MCF-7 and T47-D cell lines, whereas it was detected only in the cytosol of the estrogen receptor-negative MDA-MB-231 cells. Using the same polyclonal anti-BSP antibody, we were able to identify an approximately 97-kd band on total protein extracts from the three cell lines by immunoblotting. Reverse-transcriptase PCR reactions using specific oligonucleotides performed on total RNA of nine human breast cancer biopsy samples and the three cell lines demonstrated the presence of BSP mRNA in all of the samples examined. This study is the first demonstration that human malignant breast epithelial cell lines express BSP at the protein and mRNA levels. Our study identified MCF-7, T47-D, and MDA-MB-231 cells as useful models for the examination of the molecular mechanisms involved in the ectopic expression of BSP in breast malignant lesions. [less ▲]

Chemotaxis-Promoting and Adhesion Properties of Human Tonsillar Follicular Dendritic Cell Clusters

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 ▲]

Simulation of Human B-Lymphocyte Proliferation by Agm-1470, a Potent Inhibitor of Angiogenesis

in Journal of the National Cancer Institute (1995), 87(2), 136-9

Moabs Mas516 and 5b5, Two Fibroblast Markers, Recognize Human Follicular Dendritic Cells

in Immunology Letters (1994), 42(1-2), 49-54

Follicular dendritic cells (FDC) are only located within follicles of secondary lymphoid tissues. The origin of this peculiar cell type is not clearly defined. To contribute to this study, we applied two ... [more ▼]

Follicular dendritic cells (FDC) are only located within follicles of secondary lymphoid tissues. The origin of this peculiar cell type is not clearly defined. To contribute to this study, we applied two monoclonal antibodies (MAS516 and 5B5) considered as specific for fibroblasts to tonsil cryosections and to isolated follicular dendritic cells. On the basis of an enzyme cocktail digestion of human tonsils and a fractionation procedure on albumin gradients, FDC can be prepared in the form of cell aggregates with associated lymphoid cells. MAS516 reacts with surface membrane molecules expressed by human fibroblasts, tissue macrophages and peripheral blood monocytes. With immunoperoxidase assays on tonsil cryosections connective tissue cells and macrophages are stained. Inside germinal centres, heavy labelling of the light zone was found. The MAS516 staining pattern is very similar to that of specific FDC markers DRC-1 or BU10. All isolated FDC reacted with MAS516 antibody. 5B5, considered as a typical fibroblast marker, reacts with human prolyl-4-hydroxylase which is an intracellular enzyme related to collagen biosynthesis. In cryosections, interfollicular and capsular areas showed 5B5 positive connective tissue fibroblasts. In germinal centres, some cells presenting features of FDC were 5B5 positive. After cell separation, 25%-50% of the isolated FDC were labelled with this antibody. This positivity of some FDC for 5B5 antibody may support the idea of their fibroblastic origin. The combination of observations realized in situ and after cell purification ensured an unequivocal recognition and identification of FDC.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]

Expression and function of DRC-1 antigen.

in Advances in Experimental Medicine and Biology (1994), 355

Ultrastructure of CD57+ cells isolated from human tonsils or blood.

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 ▲]

Rapid and Selective Isolation of Follicular Dendritic Cells by Low Speed Centrifugations on Discontinuous Bsa Gradients

in Advances in Experimental Medicine and Biology (1993), 329

The germinal centre: a monastery or a bar?

in Research in Immunology (1991), 142(3), 242-4

Ultrastructural and cytochemical studies on extranucleolar bodies in rat oocytes at the preovulatory follicle stage.

in Biology of the Cell (1989), 65(1), 61-6

At the antral follicle stage, the nucleolus is entirely composed of a homogeneous proteinic compact mass. This nucleolar compaction during oogenesis seems to be a general feature in mammalian oocytes ... [more ▼]

At the antral follicle stage, the nucleolus is entirely composed of a homogeneous proteinic compact mass. This nucleolar compaction during oogenesis seems to be a general feature in mammalian oocytes. However, when oocyte maturation is induced by gonadotropin hormone (LH), oocytes enter into preovulatory stage. All the nucleoli are vacuolated and extranucleolar bodies appear in the germinal vesicle near the nucleolar mass. Based on the results obtained by ultrastructural cytochemical stainings, we postulate that these extranucleolar bodies originate from the nucleolar mass itself. The presence of the extranucleolar bodies could reflect the extrusion of nucleolar material, essentially ribonucleoproteins, into the ooplasm. This material could persist after fertilization in the pronuclei until the resumption of transcription at the early stage of embryogenesis. [less ▲]