Search results for " tolerance"

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…

Protection from graft-versus-host disease by HIV-1 envelope protein gp120-mediated activation of human CD4+CD25+ regulatory T cells.

2009

AbstractNaturally occurring CD4+CD25+ regulatory T cells (Tregs) represent a unique T-cell lineage that is endowed with the ability to actively suppress immune responses. Therefore, approaches to modulate Treg function in vivo could provide ways to enhance or reduce immune responses and lead to novel therapies. Here we show that the CD4 binding human immunodeficiency virus-1 envelope glycoprotein gp120 is a useful and potent tool for functional activation of human Tregs in vitro and in vivo. Gp120 activates human Tregs by binding and signaling through CD4. Upon stimulation with gp120, human Tregs accumulate cyclic adenosine monophosphate (cAMP) in their cytosol. Inhibition of endogeneous cA…

ROTATIONAL TOLERANCES IN ABUTMENT-IMPLANT CONNECTION FOR ORIGINAL AND COMPATIBLE ABUTMENTS

2022

Exploring a regulatory role for mast cells: 'MCregs'?

2010

Regulatory cells can mould the fate of the immune response by direct suppression of specific subsets of effector cells, or by redirecting effectors against invading pathogens and infected or neoplastic cells. These functions have been classically, although not exclusively, ascribed to different subsets of T cells. Recently, mast cells have been shown to regulate physiological and pathological immune responses, and thus to act at the interface between innate and adaptive immunity assuming different functions and behaviors at discrete stages of the immune response. Here, we focus on these poorly defined, and sometimes apparently conflicting, functions of mast cells.

An advanced and distributed control architecture based on intelligent agents and neural networks

2004

A new layered architecture for the implementation of intelligent distributed control systems is proposed. The proposed architecture distinguishes four layers in a distributed control system. Upper layer consists of a digital control layer, where high level decisions are taken. This level is implemented by means of intelligent agents that carry out the discrete control functions, system supervision as well as diagnosis and fault tolerance. Third layer deals with numeric values, performs analog operations and implement analog control loops. It is also in carry of the conversion from numerical variables values to evaluated expressions. This layer has been implemented by means of neural network…

Abnormalities in serum concentrations of interleukin-2, interferon-alpha and interferon-gamma in schizophrenia not detected.

1992

The hypothesis of an immunological defect in schizophrenia has been supported by reports on abnormal production of interleukin-2 (IL-2) and interferons (IFNs) in schizophrenic patients. In the present study we determined the serum concentrations of IL-2, IFN-alpha and IFN-gamma in 10 first onset, neuroleptic-naive schizophrenics, in 6 pretreated patients who were drug free (1 week to 2 years) at the time of the investigation and in 15 matched healthy controls. No IFN-alpha was detected in schizophrenics' and in control sera. No differences were found in IL-2 and IFN-gamma levels between schizophrenics and controls. Thus the present study failed to support the hypothesis of an immunological …