Search results for "tolerance"
showing 10 items of 956 documents
Incidence of PV module rated power tolerances on PV system energy production
2016
Discussing the electrical energy production of a PV system realized by PV modules with a large range of tolerance for the rated power values is the aim of this paper. In particular, the paper shows how the incidence of tolerance can be significant, in terms of output power reduction, when the PV system works in partial shading condition. For this issue, using a tool developed for this purpose, several simulations have been run, which consider different tolerance values for the module rated power and different shading patterns for the PV array. The authors quantify the peak power values of the different system configurations, showing the importance of the choice of modules with reduced toler…
Interferon-α Abrogates Tolerance Induction by Human Tolerogenic Dendritic Cells
2011
Background Administration of interferon-α (IFN-α) represents an approved adjuvant therapy as reported for malignancies like melanoma and several viral infections. In malignant diseases, tolerance processes are critically involved in tumor progression. In this study, the effect of IFN-α on tolerance induction by human tolerogenic dendritic cells (DC) was analyzed. We focussed on tolerogenic IL-10-modulated DC (IL-10 DC) that are known to induce anergic regulatory T cells (iTregs). Methodology/Principal Findings IFN-α promoted an enhanced maturation of IL-10 DC as demonstrated by upregulation of the differentiation marker CD83 as well as costimulatory molecules. IFN-α treatment resulted in an…
Expression profiling of autoimmune regulator AIRE mRNA in a comprehensive set of human normal and neoplastic tissues.
2006
Defects in the autoimmune regulator (AIRE) gene cause the monogenic autoimmune disease autoimmune polyendocrinopathy syndrome type 1 (APS-1), which is characterized by a loss of self-tolerance to multiple organs. In concordance with its role in immune tolerance, AIRE is strongly expressed in medullary thymic epithelial cells (mTECs). Data on mechanisms controlling AIRE activation and the expression of this gene in other tissues are fragmentary and controversial. We report here AIRE mRNA expression profiling of a large set of normal human tissues and cells, tumor specimen and methylation deficient cell lines. On this broad data basis we found that AIRE mRNA expression is confined to mTECs in…
Dendritic cells: sentinels of immunity and tolerance.
2005
The induction of effective antigen-specific T-cell immunity to pathogens without the initiation of autoimmunity has evolved as a sophisticated and highly balanced immunoregulatory mechanism. This mechanism assures the generation of antigen-specific effector cells as well as the induction and maintenance of antigen-specific tolerance to self-structures of the body. As professional antigen-presenting cells of the immune system, dendritic cells (DC) are ideally positioned throughout the entire body and equipped with a unique capability to transport antigens from the periphery to lymphoid tissues. There is growing evidence that DC, besides their well-known immunostimulatory properties, also ind…
Revisiting Current Concepts on the Tolerogenicity of Steady-State Dendritic Cell Subsets and Their Maturation Stages
2021
Abstract The original concept stated that immature dendritic cells (DC) act tolerogenically whereas mature DC behave strictly immunogenically. Meanwhile, it is also accepted that phenotypically mature stages of all conventional DC subsets can promote tolerance as steady-state migratory DC by transporting self-antigens to lymph nodes to exert unique functions on regulatory T cells. We propose that in vivo 1) there is little evidence for a tolerogenic function of immature DC during steady state such as CD4 T cell anergy induction, 2) all tolerance as steady-state migratory DC undergo common as well as subset-specific molecular changes, and 3) these changes differ by quantitative and qualitati…
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…
Cyclic adenosine monophosphate and IL-10 coordinately contribute to nTreg cell-mediated suppression of dendritic cell activation
2010
In humans and mice naturally occurring regulatory T cells (nTregs) are crucial for the maintenance of peripheral tolerance by controlling not only potentially autoreactive T cells but virtually all cells of the adaptive and innate immune system. Here we show that co-culture of murine dendritic cells (DC) and nTregs results in an immediate increase of cAMP in DC, responsible for a rapid down-regulation of co-stimulatory molecules (CD80, CD86). In addition, the inhibitory surface molecule B7-H3 on DC is up-regulated. Subsequently, nTreg-derived IL-10 inhibits the cytokine production (IL-6, IL-12) of suppressed DC therewith preserving their silent phenotype. Hence, our data indicate that nTreg…
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…
Reciprocal IFN-gamma and TGF-beta responses regulate the occurrence of mucosal inflammation.
1997
The above new findings concerning the immunological mechanisms governing mucosa, immune responses and oral tolerance in TCR-transgenic mice, as well as those operative in mice with experimental colitis, greatly expand our understanding of the processes that normally control mucosal inflammation and possibly other types of inflammation as well (Fig. 1). They indicate that, in the nondiseased mouse, ingested proteins evoke a Th1-cell (IFN-gamma) response in the mucosal follicles that is quickly counter-regulated by induction of T-cell anergy/deletion, if this Th1-cell response is inhibited (experimentally by anti-IL-12), TGF beta-producing cells appear, and these are capable of active immune …
Antigens expressed by myelinating glia cells induce peripheral cross‐tolerance of endogenous CD8+T cells
2009
Auto-reactivity of T cells is largely prevented by central and peripheral tolerance. Nevertheless, immunization with certain self-antigens emulsified in CFA induces autoimmunity in rodents, suggesting that tolerance to some self-antigens is not robust. To investigate the fate of nervous system-specific CD8(+) T cells, which only recently came up as being important contributors for MS pathogenesis, we developed a mouse model that allows inducible expression of lymphocytic choriomeningitis virus-derived CD8(+) T-cell epitopes specifically in oligodendrocytes and Schwann cells, the myelinating glia of the nervous system. These transgenic CD8(+) T-cell epitopes induced robust tolerance of endog…