Publications (3)24.79 Total impact
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Article: Interactions of TANGO and leukocyte integrin CD11c/CD18 regulate the migration of human monocytes.
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ABSTRACT: The TANGO gene was originally identified as a new member of the MIA gene family. It codes for a protein of yet unknown function. TANGO revealed a very broad expression pattern in contrast to the highly restricted expression pattern determined for the other family members. The only cells lacking TANGO expression are cells of the hematopoietic system. One of the major differences between mature hematopoietic cells and other tissue cells is the lack of adhesion until these cells leave the bloodstream. In this study, we observed that TANGO expression was induced after adhesion of human monocytic cells to substrate. To understand the mechanism of TANGO function during monocyte adhesion we isolated interacting proteins and found an interaction between TANGO and the leukocyte-specific integrin CD11c. In functional assays, we observed reduced attachment of human monocytic cells to fibrinogen, ICAM-1 and to human microvascular endothelial cells (HMECs) after stimulation with recombinant TANGO protein. Additionally, the migrating capacity of premonocytic cells through fibrinogen or HMECs was increased after stimulation of these cells with recombinant TANGO. Therefore, we suggest that TANGO reduced the attachment to fibrinogen or other cell adhesion molecules. As TANGO does not compete for CD11c ligand binding directly, we hypothesize TANGO function by modulation of integrin activity. Taken together, the results from this study present TANGO as a novel ligand for CD11c, regulating migratory processes of hematopoietic cells.Journal of Leukocyte Biology 01/2008; 82(6):1466-72. · 4.99 Impact Factor -
Article: Isolation and characterization of human antigen-specific TCR alpha beta+ CD4(-)CD8- double-negative regulatory T cells.
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ABSTRACT: Down-regulation of immune responses by regulatory T (Treg) cells is an important mechanism involved in the induction of tolerance to allo-antigens (Ags). Recently, a novel subset of Ag-specific T-cell receptor (TCR)alpha beta+ CD4(-)CD8- (double-negative [DN]) Treg cells has been found to be able to prevent the rejection of skin and heart allografts by specifically inhibiting the function of antigraft-specific CD8+ T cells. Here we demonstrate that peripheral DN Treg cells are present in humans, where they constitute about 1% of total CD3+ T cells, and consist of both naive and Ag-experienced cells. Similar to murine DN Treg cells, human DN Treg cells are able to acquire peptide-HLA-A2 complexes from antigen-presenting cells by cell contact-dependent mechanisms. Furthermore, such acquired peptide-HLA complexes appear to be functionally active, in that CD8+ T cells specific for the HLA-A2-restricted self-peptide, Melan-A, became sensitive to apoptosis by neighboring DN T cells after acquisition of Melan-A-HLA-A2 complexes and revealed a reduced proliferative response. These results demonstrate for the first time that a sizable population of peripheral DN Treg cells, which are able to suppress Ag-specific T cells, exists in humans. DN Treg cells may serve to limit clonal expansion of allo-Ag-specific T cells after transplantation.Blood 05/2005; 105(7):2828-35. · 9.90 Impact Factor -
Article: Regulation of 25-hydroxyvitamin D3-1 alpha-hydroxylase and production of 1 alpha,25-dihydroxyvitamin D3 by human dendritic cells.
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ABSTRACT: 25-Hydroxyvitamin D3-1 alpha-hydroxylase (25(OH)D3-1 alpha-hydroxylase), the key enzyme of 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) production, is expressed in monocyte-derived macrophages (MACs). Here we show for the first time constitutive expression of 25(OH)D3-1 alpha-hydroxylase in monocyte-derived dendritic cells (DCs), which was increased after stimulation with lipopolysaccharide (LPS). Accordingly, DCs showed low constitutive production of 1,25(OH)2D3, but activation by LPS increased 1,25(OH)2D3 synthesis. In addition, 25(OH)D3-1 alpha-hydroxylase expression was found in blood DCs but not in CD34+-derived DCs. Next we analyzed the functional consequences of these results. Addition of 1,25(OH)2D3 at concentrations comparable with those produced by DCs inhibited the allostimulatory potential of DCs during the early phase of DC differentiation. However, terminal differentiation decreased the responsiveness of DCs to 1,25(OH)2D3. In conclusion, DCs are able to produce 1,25(OH)2D3 especially following stimulation with LPS. Terminal maturation renders DCs unresponsive to the effects of 1,25(OH)2D3, but those cells are able to suppress the differentiation of their own precursor cells in a paracrine way through the production of 1,25(OH)2D3.Blood 12/2003; 102(9):3314-6. · 9.90 Impact Factor
