Search results for " ACTIVATION"
showing 10 items of 1535 documents
Tuning tumor-specific T-cell activation: a matter of costimulation?
2002
Abstract The stimulation of a specific antitumor immune response, involving the recruitment of T cells and induction of T-cell effector functions, is an attractive possibility for cancer immunotherapy. In the past few years, advances in our understanding of the mechanisms of T-cell activation and costimulation have provided the basis for strategies to enhance antitumor immunity and break tolerance. These strategies include the equipment of tumor cells with costimulatory molecules such as B7, blockade of inhibitory signals on T cells (e.g. through cytotoxic T-lymphocyte antigen 4) and grafting of T cells with antigen-triggered, recombinant costimulatory receptors. Combining antigen-triggered…
Identification and Functional Characterization of Human Cd4+Cd25+ T Cells with Regulatory Properties Isolated from Peripheral Blood
2001
A subpopulation of peripheral human CD4(+)CD25(+) T cells that expresses CD45RO, histocompatibility leukocyte antigen DR, and intracellular cytotoxic T lymphocyte-associated antigen (CTLA) 4 does not expand after stimulation and markedly suppresses the expansion of conventional T cells in a contact-dependent manner. After activation, CD4(+)CD25(+) T cells express CTLA-4 on the surface detectable for several weeks. These cells show a G1/G0 cell cycle arrest and no production of interleukin (IL)-2, IL-4, or interferon (IFN)-gamma on either protein or mRNA levels. The anergic state of CD4(+)CD25(+) T cells is not reversible by the addition of anti-CD28, anti-CTLA-4, anti-transforming growth fa…
Human CD4+CD25+ T cells derived from the majority of atopic donors are able to suppress TH1 and TH2 cytokine production
2003
Abstract Background: Recently, it has been established that CD4 + CD25 + T cells with regulatory capacity are present in human peripheral blood, inhibiting allogeneic proliferation and cytokine production of preactivated CD4 + CD25 − respond-er T cells. Objective: The aim of this study was to analyze in an allergen-specific setting whether such regulatory CD4 + CD25 + T cells also exist and function normally in atopic individuals, especially concerning the inhibition of T H 2 cytokines. Methods: For this purpose, CD4 + CD25 − or CD4 + CD25 + T cells from donors allergic to grass or birch pollen (mainly with rhinitis) or from healthy nonatopic donors were stimulated in the presence of autolo…
Hapten synthesis, monoclonal antibody generation, and development of competitive immunoassays for the analysis of picoxystrobin in beer.
2010
Abstract This paper describes the original synthesis of a functionalized derivative of the fungicide picoxystrobin and the generation of the first reported monoclonal antibodies against this strobilurin pesticide. The synthetic hapten was prepared by total synthesis from commercial chemicals and incorporating the spacer arm through a carbon–carbon single bond. Also, to obtain the immunogen, an uncommon hapten activation strategy based on N,N′-disuccinimidyl carbonate was employed, affording high activation yields and clean and reproducible coupling results. With these immunoreagents, two enzyme-linked immunosorbent assays (ELISAs) were developed: a competitive one-step assay using the antib…
Mast cells enhance proliferation of B lymphocytes and drive their differentiation toward IgA-secreting plasma cells.
2010
AbstractThe evidence of a tight spatial interaction between mast cells (MCs) and B lymphocytes in secondary lymphoid organs, along with the data regarding the abundance of MCs in several B-cell lymphoproliferative disorders prompted us to investigate whether MCs could affect the proliferation and differentiation of B cells. To this aim, we performed coculture assays using mouse splenic B cells and bone marrow–derived MCs. Both nonsensitized and activated MCs proved able to induce a significant inhibition of cell death and an increase in proliferation of naive B cells. Such proliferation was further enhanced in activated B cells. This effect relied on cell-cell contact and MC-derived interle…
A20 deficiency in B cells enhances B-cell proliferation and results in the development of autoantibodies.
2011
A20/TNFAIP3 is an ubiquitin-editing enzyme, important for the regulation of the NF-κB pathway. Mutations in the TNFAIP3 gene have been linked to different human autoimmune disorders. In human B-cell lymphomas, the inactivation of A20 results in constitutive NF-κB activation. Recent studies demonstrate that in mice the germline inactivation of A20 leads to early lethality, due to inflammation in multiple organs of the body. In this report, we describe a new mouse strain allowing for the tissue-specific deletion of A20. We show that B-cell-specific deletion of A20 results in a dramatic reduction in marginal zone B cells. Furthermore, A20-deficient B cells display a hyperactive phenotype repre…
Synthesis and expression of MHC class II molecules in the absence of attached invariant chains by recombinant-interferon-gamma-activated bone-marrow-…
1987
Pure populations of in vitro propagated bone marrow-derived macrophages are constitutively Ia negative. Co-culturing of these cells with recombinant interferon-gamma (rIFN-gamma) resulted in the appearance of high amounts of Ia antigens at the cell surface of essentially all cells. The continuous presence of the stimulus was a prerequisite for sustained Ia expression because removal of the stimulus resulted in rapid decline of surface Ia. Two-dimensional (2D) gel analysis (1D isoelectric focusing, 2D sodium dodecyl sulfate-polyacrylamide gel electrophoresis) of class II molecules synthesized by rIFN-gamma-stimulated bone marrow macrophages (BMM phi) revealed that, in contrast to class II co…
Quantitative studies of the secretion of complement component C3 by resident, elicited and activated macrophages. Comparison with C2, C4 and lysosoma…
1982
To quantitate the secretion of complement component C3 by guinea pig peritoneal macrophages an enzyme-linked immunosorbent assay was developed. C3 secretion was studied in resident, elicited and activated macrophages and compared with release of hemolytically active C2 and C4, as well as the lysosomal enzyme β-D-2-acetamido-2-deoxyglucosidase. Resident macrophages secreted about 6 ng C3/106 cells/h into culture supernatants over a period of 12 h. Corynebacterium parvum-activated cells were found to secrete 3 times that amount at nearly constant rates. There was a stepwise increase in secretion of functional C2 and C4 when comparing resident, elicited and activated macrophages; secretion was…
Modulation of C1q mRNA Expression and Secretion by Interleukin-1,Interleukin-6, and Interferon-g in Resident and Stimulated Murine Peritoneal Macroph…
2002
The complement system plays an important role in the humoral immune response. Activation of the classical complement pathway is mediated by its subcomponent, C1q. Among the main C1q-synthesising tissues, macrophages have been attributed as a source of particular importance. We investigated the effects of cytokines (IL-1, IL-6 and Interferon-gamma) on local C1q mRNA expression and C1q secretion in resident and in thioglycollate-stimulated murine peritoneal macrophages in vitro. The macrophages were isolated from murine peritoneal lavage fluid, maintained in culture and incubated with the cytokines. Among the cytokines, only IL-6 had a stimulatory effect on C1q production (25% increase vs. co…
CD4-mediated functional activation of human CD4+CD25+ regulatory T cells
2007
Naturally occurring CD4(+)CD25(+)FoxP3(+) regulatory T cells (CD25(+) Tregs) constitute a specialized population of T cells that is essential for the maintenance of peripheral self-tolerance. The immune regulatory function of CD25(+) Tregs depends upon their activation. We found that anti-CD4 antibodies activate the suppressive function of human CD25(+) Tregs in a dose-dependent manner. We demonstrate that CD4-activated CD25(+) Tregs suppress the proliferation of CD4(+) and CD8(+) T cells, their IL-2 and IFN-gamma production as well as the capacity of CD8(+) T cells to re-express CD25. By contrast, anti-CD4 stimulation did not induce suppressive activity in conventional CD4(+) T cells. Thes…