Search results for "Lymphocyte Subsets"
showing 10 items of 212 documents
The protein tyrosine kinase Tec regulates a CD44highCD62L- Th17 subset.
2010
Abstract The generation of Th17 cells has to be tightly controlled during an immune response. In this study, we report an increase in a CD44highCD62L− Th17 subset in mice deficient for the protein tyrosine kinase Tec. CD44highCD62L− Tec−/− CD4+ T cells produced enhanced IL-17 upon activation, showed increased expression levels of IL-23R and RORγt, and IL-23–mediated expansion of Tec−/− CD4+ T cells led to an increased production of IL-17. Tec−/− mice immunized with heat-killed Streptococcus pneumoniae displayed increased IL-17 expression levels in the lung postinfection with S. pneumoniae, and this correlated with enhanced pneumococcal clearance and reduced lung inflammation compared with T…
Regulatory T cells--the renaissance of the suppressor T cells.
2007
Immune reactions are stringently regulated and balanced by complex interactions of stimulating and suppressing mechanisms. Dysfunctions of this sophisticated immune regulatory network can lead to a variety of diseases such as autoimmunity, allergy, cancer, and pregnancy disorders. The rediscovery of suppressor T cells a decade ago--now designated as T regulatory cells--set off a huge avalanche of research activities leading to a multitude of preclinical and clinical studies. Herein, we give a comprehensive review about this research on T regulatory cells and the relevance of this suppressive T cell population for the development of innovative immune therapeutic strategies.
TGF-beta as a T cell regulator in colitis and colon cancer
2005
TGF-beta is a pleiotropic cytokine with powerful immunosuppressive functions. Mice deficient for TGF-beta1 show a dramatic phenotype with severe multiorgan inflammation and die shortly after birth. Recent investigations have highlighted the role of TGF-beta in suppression of T cell mediated autoimmune inflammation and anti-tumor immunity. In addition to its direct anti-inflammatory effects on T cells, TGF-beta has been implicated as central regulator of regulatory T cells. TGF-beta not only mediates the suppression of effector T cells by Tregs, recent evidence also reveals a role for TGF-beta along with TCR stimulation in the peripheral induction of regulatory T cells from naïve CD4+CD25- c…
TGF-beta regulates airway responses via T cells.
2003
Abstract Allergic asthma is characterized by airway hyperreactivity, inflammation, and a Th2-type cytokine profile favoring IgE production. Beneficial effects of TGF-β and conflicting results regarding the role of Th1 cytokines have been reported from murine asthma models. In this study, we examined the T cell as a target cell of TGF-β-mediated immune regulation in a mouse model of asthma. We demonstrate that impairment of TGF-β signaling in T cells of transgenic mice expressing a dominant-negative TGF-β type II receptor leads to a decrease in airway reactivity in a non-Ag-dependent model. Increased serum levels of IFN-γ can be detected in these animals. In contrast, after injection of OVA …
TGFbeta regulates the CD4+CD25+ T-cell pool and the expression of Foxp3 in vivo.
2004
Factors influencing the development of CD4+CD25+ T-cells in vivo are poorly understood. In order to investigate the contribution of TGFbeta1 to the development and function of CD4+CD25+ T-cells, we generated a gain of function mutation resulting in the overexpression of an active form of TGFbeta1 in T-cells under control of the human CD2 promoter. In peripheral lymphoid organs and in the thymus, the frequency of CD4+CD25+ T-cells was increased in transgenic mice. This appeared to be due to an autocrine effect of TGFbeta on T-cells, since concomitant impairment of TGFbeta-signaling in double transgenic mice resulted in a phenotype similar to wild type. In contrast, in single transgenic mice …
A distinct subset of HLA-DR+-regulatory T cells is involved in the induction of preterm labor during pregnancy and in the induction of organ rejectio…
2010
Regulatory T cells (Tregs) are known to suppress alloimmune responses during pregnancy and post organ transplantation. We demonstrate that a distinct subset of FoxP3(+)DR(+)-Tregs among the total CD4(+)CD127(low+/-)CD25(+)-Treg cell pool is critically involved in preterm labor induction and kidney transplant rejection as well. Compared to healthy pregnancies and non-rejecting kidney recipients, we found that the percentage of the FoxP3(+)DR(+)-Treg subset was not reduced, but that the level of HLA-DR expression of such Tregs was strongly diminished in preterm laboring women and in patients with acute renal allograft rejection. In addition, both patient collectives showed a significantly red…
Human cytomegalovirus (HCMV)-specific CD4+ T lymphocyte response in AIDS patients with no past or current HCMV disease following HAART.
2003
Abstract Background: The incidence of Human Cytomegalovirus (HCMV) end-organ disease has dramatically decreased since the implementation of highly active antiretroviral therapies (HAARTs), but the precise immune mechanism whereby HCMV is controlled remains to be elucidated. Objectives: To investigate the effect of (HAART) on CD4 + T-cell immunity to HCMV in AIDS patients with no past or current HCMV disease. Study design: Seventeen patients were prospectively examined for CD4 + (CD45RO + and CD45 RA + ) T-cell counts (flow cytometry), HIV RNA load (Amplicor HIV test), HCMV leukoDNAemia and HCMV DNA in urine (nested PCR), lymphoproliferative response (LPR) to HCMV, phytohemagglutinin (PHA) a…
Impact of CMV and EBV seropositivity on CD8 T lymphocytes in an old population from West-Sicily.
2007
Abstract Herpes viruses (particularly CMV and to some extent EBV) might play a role in accelerating the deterioration of immune functions with age. Indeed, it has been demonstrated that chronic infection with CMV causes an expansion of specific CD8 T lymphocytes and that this is related to a shrinkage of the T cell repertoire in very elderly people, predicting mortality. We have analysed CD8 T cells in young and old healthy Sicilians who were both CMV- and EBV-seropositive. Our data confirm expansions of T cells specific for the HLA-A2-restricted pp65 (495–503) CMV epitope up to nearly 14% of total peripheral CD8 cells in certain elderly individuals (range 0–14%). However, the mean percenta…
γδT cells elicited by CMV reactivation after allo-SCT cross-recognize CMV and leukemia.
2013
Human cytomegalovirus (CMV) infections and relapse of disease remain major problems after allogeneic stem cell transplantation (allo-SCT), in particular in combination with CMV-negative donors or cordblood transplantations. Recent data suggest a paradoxical association between CMV reactivation after allo-SCT and reduced leukemic relapse. Given the potential of Vδ2-negative γδT cells to recognize CMV-infected cells and tumor cells, the molecular biology of distinct γδT-cell subsets expanding during CMV reactivation after allo-SCT was investigated. Vδ2(neg) γδT-cell expansions after CMV reactivation were observed not only with conventional but also cordblood donors. Expanded γδT cells were ca…
Are human Vδ2(pos) T cells really resistant to aging and Human Cytomegalovirus infection?()
2019
In their recent paper, Weili Xu et al. [1] described the different behaviors of Vδ1pos and Vδ2pos T cell subsets in response to lifelong stress and claimed that Vδ2pos T cells are not affected by aging and Human Cytomegalovirus (HCMV) infection. While we agree that these two γδ T cell subsets diverge both in phenotype/function and in tissue distribution, we are somewhat surprised that authors did not take into account the several previously published and contradictory experimental evidence in regards to senescence of Vδ2pos T cells [2,3]. These latter studies reported that HCMV infection not only induces a clonal expansion of a distinct Vγ9neg/Vδ2pos T cell subset, but also determines a con…