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Cloned T cells have been useful for assessing the lytic potential of distinct T cell subsets and for determining the relative contribution of different effector mechanism involved in the lytic process. Alloreactive CD8+ murine T cell clones and cloned murine CD4+ TH1 and TH2 T cells reactive with nominal antigen (ovalbumin) lysed nucleated target cells bearing antigen or coated with anti-CD3 monoclonal antibody in a short term51Cr-release assay. These clones were also evaluated for their ability to lyse efficiently sheep erythrocyte (SRBC) target cells coated with anti-CD3 mAb by a mechanism (presumably involving membrane damage) that does not involve nuclear degradation. Three patterns of lysis were observed: CD8+ and some CD4+ TH2 effector cells lysed efficiently nucleated target cells and anucleated SRBC coated with anti-CD3 mAb. However, CD4+ TH1 (and a few TH2) T cells which lysed nucleated target cells bearing antigen or coated with anti-CD3 mAb didnotlyse efficiently the SRBC coated with anti-CD3 mAb. One CD4 bearing TH2 cell failed to lyse efficiently either nucleated target cells or anucleated SRBC coated with anti-CD3 mAb. These results indicate that both TH1 and TH2 clones have lytic capabilities. Furthermore, they suggest that some but not all TH2 murine T cell clones have lytic characteristics similar to those of conventional CD8+ CTL. However, it is not certain how these patterns of lysis of target cellsin vitro relates to the capacity of CTL to lyse such target cellsin vivo.  相似文献   

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Loss of intestinal CD4+ T cells was associated with decreased production of several T-helper 1 (TH1) and TH2 cytokines and increased production of interleukin 17 (IL-17), gamma interferon (IFN-γ), CCL4, and granulocyte-macrophage colony-stimulating factor (GM-CSF) by CD8+ T cells 21 days after simian immunodeficiency virus (SIV) infection in rhesus macaques. Shifting of mucosal TH1 to TH2 or T-cytotoxic 1 (TC1) to TC2 cytokine profiles was not evident. Additionally, both CD4+ and CD8+ T cells showed upregulation of macrophage migration inhibition factor (MIF) and basic fibroblast growth factor (FGF-basic) cytokines that have been linked to HIV disease progression.  相似文献   

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Regulatory T cells (Treg) have been shown to restrict vaccine-induced T cell responses in different experimental models. In these studies CD4+CD25+ Treg were depleted using monoclonal antibodies against CD25, which might also interfere with CD25 on non-regulatory T cell populations and would have no effect on Foxp3+CD25 Treg. To obtain more insights in the specific function of Treg during vaccination we used mice that are transgenic for a bacterial artificial chromosome expressing a diphtheria toxin (DT) receptor-eGFP fusion protein under the control of the foxp3 gene locus (depletion of regulatory T cell mice; DEREG). As an experimental vaccine-carrier recombinant Bordetella adenylate cyclase toxoid fused with a MHC-class I-restricted epitope of the circumsporozoite protein (ACT-CSP) of Plasmodium berghei (Pb) was used. ACT-CSP was shown by us previously to introduce the CD8+ epitope of Pb-CSP into the MHC class I presentation pathway of professional antigen-presenting cells (APC). Using this system we demonstrate here that the number of CSP-specific T cells increases when Treg are depleted during prime but also during boost immunization. Importantly, despite this increase of T effector cells no difference in the number of antigen-specific memory cells was observed.  相似文献   

8.
Because T cell differentiation leads to an expanded repertoire of chemokine receptors, a subgroup of G protein-coupled receptors, we hypothesized that the repertoire of G proteins might be altered in parallel. We analyzed the abundance of mRNA and/or protein of six G protein α-subunits in human CD4+ and CD8+ T cell subsets from blood. Although most G protein α-subunits were similarly expressed in all subsets, the abundance of Gαo, a protein not previously described in hematopoietic cells, was much higher in memory versus naive cells. Consistent with these data, activation of naive CD4+ T cells in vitro significantly increased the abundance of Gαo in cells stimulated under nonpolarizing or TH17 (but not TH1 or TH2)-polarizing conditions. In functional studies, the use of a chimeric G protein α-subunit, Gαqo5, demonstrated that chemokine receptors could couple to Gαo-containing G proteins. We also found that Gαi1, another α-subunit not described previously in leukocytes, was expressed in naive T cells but virtually absent from memory subsets. Corresponding to their patterns of expression, siRNA-mediated knockdown of Gαo in memory (but not naive) and Gαi1 in naive (but not memory) CD4+ T cells inhibited chemokine-dependent migration. Moreover, although even in Gαo- and Gαi1-expressing cells mRNAs of these α-subunits were much less abundant than Gαi2 or Gαi3, knockdown of any of these subunits impaired chemokine receptor-mediated migration similarly. Together, our data reveal a change in the repertoire of Gαi/o subunits during T cell differentiation and suggest functional equivalence among Gαi/o subunits irrespective of their relative abundance.  相似文献   

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Despite their limited proliferation capacity, regulatory T cells (Tregs) constitute a population maintained over the entire lifetime of a human organism. The means by which Tregs sustain a stable pool in vivo are controversial. Using a mathematical model, we address this issue by evaluating several biological scenarios of the origins and the proliferation capacity of two subsets of Tregs: precursor CD4+CD25+CD45RO and mature CD4+CD25+CD45RO+ cells. The lifelong dynamics of Tregs are described by a set of ordinary differential equations, driven by a stochastic process representing the major immune reactions involving these cells. The model dynamics are validated using data from human donors of different ages. Analysis of the data led to the identification of two properties of the dynamics: (1) the equilibrium in the CD4+CD25+FoxP3+Tregs population is maintained over both precursor and mature Tregs pools together, and (2) the ratio between precursor and mature Tregs is inverted in the early years of adulthood. Then, using the model, we identified three biologically relevant scenarios that have the above properties: (1) the unique source of mature Tregs is the antigen-driven differentiation of precursors that acquire the mature profile in the periphery and the proliferation of Tregs is essential for the development and the maintenance of the pool; there exist other sources of mature Tregs, such as (2) a homeostatic density-dependent regulation or (3) thymus- or effector-derived Tregs, and in both cases, antigen-induced proliferation is not necessary for the development of a stable pool of Tregs. This is the first time that a mathematical model built to describe the in vivo dynamics of regulatory T cells is validated using human data. The application of this model provides an invaluable tool in estimating the amount of regulatory T cells as a function of time in the blood of patients that received a solid organ transplant or are suffering from an autoimmune disease.  相似文献   

10.
In contrast to the ability of long-lived CD8+ memory T cells to mediate protection against systemic viral infections, the relationship between CD4+ T cell memory and acquired resistance against infectious pathogens remains poorly defined. This is especially true for T helper 1 (Th1) concomitant immunity, in which protection against reinfection coincides with a persisting primary infection. In these situations, pre-existing effector CD4 T cells generated by ongoing chronic infection, not memory cells, may be essential for protection against reinfection. We present a systematic study of the tissue homing properties, functionality, and life span of subsets of memory and effector CD4 T cells activated in the setting of chronic Leishmania major infection in resistant C57Bl/6 mice. We found that pre-existing, CD44+CD62LT-bet+Ly6C+ effector (TEFF) cells that are short-lived in the absence of infection and are not derived from memory cells reactivated by secondary challenge, mediate concomitant immunity. Upon adoptive transfer and challenge, non-dividing Ly6C+ TEFF cells preferentially homed to the skin, released IFN-γ, and conferred protection as compared to CD44+CD62LLy6C effector memory or CD44+CD62L+Ly6C central memory cells. During chronic infection, Ly6C+ TEFF cells were maintained at high frequencies via reactivation of TCM and the TEFF themselves. The lack of effective vaccines for many chronic diseases may be because protection against infectious challenge requires the maintenance of pre-existing TEFF cells, and is therefore not amenable to conventional, memory inducing, vaccination strategies.  相似文献   

11.
It has been reported that the immune response mediated by T CD8+ lymphocytes plays a critical role in the control of Trypanosoma cruzi infection and that the clinical symptoms of Chagas disease appear to be related to the competence of the CD8+ T immune response against the parasite. Herewith, in silico prediction and binding assays on TAP-deficient T2 cells were used to identify potential HLA-A*02:01 ligands in the T. cruzi TcCA-2 protein. The TcCA-2-specific CD8+ T cells were functionality evaluated by Granzyme B and cytokine production in peripheral blood mononuclear cells (PBMC) from Chagas disease patients stimulated with the identified HLA-A*02:01 peptides. The specific cells were phenotypically characterized by flow cytometry using several surface markers and HLA-A*02:01 APC-labeled dextramer loaded with the peptides. In the T. cruzi TcCA-2 protein four T CD8+ epitopes were identified which are processed and presented during Chagas disease. Interestingly, a differential cellular phenotypic profile could be correlated with the severity of the disease. The TcCA-2-specific T CD8+ cells from patients with cardiac symptoms are mainly effector memory cells (TEM and TEMRA) while, those present in the asymptomatic phase are predominantly naive cells (TNAIVE). Moreover, in patients with cardiac symptoms the percentage of cells with senescence features is significantly higher than in patients at the asymptomatic phase of the disease. We consider that the identification of these new class I-restricted epitopes are helpful for designing biomarkers of sickness pathology as well as the development of immunotherapies against T. cruzi infection.  相似文献   

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Peripheral CD4+CD8+ T cells have been identified as a T cell subset existing in animals and humans. However, the characterization of CD4+CD8+ T cells, their relationship with T memory (TM), T effector (TE), Th1/Th2, Treg and Th-17, remain unclear. This study was to characterize the CD4+CD8+ T cells. The results from human subjects showed that activated T cells were CD4+CD8+ T cells, comprised CD4hiCD8lo, CD4hiCD8hi and CD4loCD8hi subsets. They expressed CD62Lhi/lo, granzyme B (GrB), CD25, Foxp3, interleukin 17 (IL-17) and the cytokines of both Th1 and Th2, and had cytolytic function. These findings suggested that CD4+CD8+ T cells had over-lap function while they kept diversity, and that T cells could be divided into two major populations: activated and inactivated. Hence, the hypotheses of Th1/Th2, Treg and Th-17 might reflect the positive/negative feedback regulation of immune system. When compared to GrB+CD62Llo T effector (TE) cells, GrB+CD62Lhi T central memory effector (TCME) cells had a quicker response to virus without CD62L loss.  相似文献   

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Antigenic variation to evade host immunity has long been assumed to be a driving force of diversifying selection in pathogens. Colonization by Streptococcus pneumoniae, which is central to the organism''s transmission and therefore evolution, is limited by two arms of the immune system: antibody- and T cell- mediated immunity. In particular, the effector activity of CD4+ TH17 cell mediated immunity has been shown to act in trans, clearing co-colonizing pneumococci that do not bear the relevant antigen. It is thus unclear whether TH17 cell immunity allows benefit of antigenic variation and contributes to diversifying selection. Here we show that antigen-specific CD4+ TH17 cell immunity almost equally reduces colonization by both an antigen-positive strain and a co-colonized, antigen-negative strain in a mouse model of pneumococcal carriage, thus potentially minimizing the advantage of escape from this type of immunity. Using a proteomic screening approach, we identified a list of candidate human CD4+ TH17 cell antigens. Using this list and a previously published list of pneumococcal Antibody antigens, we bioinformatically assessed the signals of diversifying selection among the identified antigens compared to non-antigens. We found that Antibody antigen genes were significantly more likely to be under diversifying selection than the TH17 cell antigen genes, which were indistinguishable from non-antigens. Within the Antibody antigens, epitopes recognized by human antibodies showed stronger evidence of diversifying selection. Taken together, the data suggest that TH17 cell-mediated immunity, one form of T cell immunity that is important to limit carriage of antigen-positive pneumococcus, favors little diversifying selection in the targeted antigen. The results could provide new insight into pneumococcal vaccine design.  相似文献   

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Following thymic output, αβ+CD4+ T cells become activated in the periphery when they encounter peptide–major histocompatibility complex. A combination of cytokine and co-stimulatory signals instructs the differentiation of T cells into various lineages and subsequent expansion and contraction during an appropriate and protective immune response. Our understanding of the events leading to T-cell lineage commitment has been dominated by a single fate model describing the commitment of T cells to one of several helper (TH), follicular helper (TFH) or regulatory (TREG) phenotypes. Although a single lineage-committed and dedicated T cell may best execute a single function, the view of a single fate for T cells has recently been challenged. A relatively new paradigm in αβ+CD4+ T-cell biology indicates that T cells are much more flexible than previously appreciated, with the ability to change between helper phenotypes, between helper and follicular helper, or, most extremely, between helper and regulatory functions. In this review, we comprehensively summarize the recent literature identifying when TH or TREG cell plasticity occurs, provide potential mechanisms of plasticity and ask if T-cell plasticity is beneficial or detrimental to immunity.  相似文献   

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Pathology studies of progressive multiple sclerosis (MS) indicate a major role of inflammation including Th17-cells and meningeal inflammation with ectopic lymphoid follicles, B-cells and plasma cells, the latter indicating a possible role of the newly identified subset of follicular T-helper (TFH) cells. Although previous studies reported increased systemic inflammation in progressive MS it remains unclear whether systemic inflammation contributes to disease progression and intrathecal inflammation. This study aimed to investigate systemic inflammation in progressive MS and its relationship with disease progression, using flow cytometry and gene expression analysis of CD4+ and CD8+T-cells, B-cells, monocytes and dendritic cells. Furthermore, gene expression of cerebrospinal fluid cells was studied. Flow cytometry studies revealed increased frequencies of ICOS+TFH-cells in peripheral blood from relapsing-remitting (RRMS) and secondary progressive (SPMS) MS patients. All MS subtypes had decreased frequencies of Th1 TFH-cells, while primary progressive (PPMS) MS patients had increased frequency of Th17 TFH-cells. The Th17-subset, interleukin-23-receptor+CD4+T-cells, was significantly increased in PPMS and SPMS. In the analysis of B-cells, we found a significant increase of plasmablasts and DC-SIGN+ and CD83+B-cells in SPMS. ICOS+TFH-cells and DC-SIGN+B-cells correlated with disease progression in SPMS patients. Gene expression analysis of peripheral blood cell subsets substantiated the flow cytometry findings by demonstrating increased expression of IL21, IL21R and ICOS in CD4+T-cells in progressive MS. Cerebrospinal fluid cells from RRMS and progressive MS (pooled SPMS and PPMS patients) had increased expression of TFH-cell and plasmablast markers. In conclusion, this study is the first to demonstrate the potential involvement of activated TFH-cells in MS. The increased frequencies of Th17-cells, activated TFH- and B-cells parallel findings from pathology studies which, along with the correlation between activated TFH- and B-cells and disease progression, suggest a pathogenic role of systemic inflammation in progressive MS. These observations may have implications for the treatment of progressive MS.  相似文献   

16.

Background

The recruitment of CD4+CD25+Foxp3+T (Treg) cells is one of the most important mechanisms by which parasites down-regulate the immune system.

Methodology/Principal Findings

We compared the effects of Treg cells from Trichinella spiralis-infected mice and uninfected mice on experimental allergic airway inflammation in order to understand the functions of parasite-induced Treg cells. After four weeks of T. spiralis infection, we isolated Foxp3-GFP-expressing cells from transgenic mice using a cell sorter. We injected CD4+Foxp3+ cells from T. spiralis-infected [Inf(+)Foxp3+] or uninfected [Inf(-)Foxp3+] mice into the tail veins of C57BL/6 mice before the induction of inflammation or during inflammation. Inflammation was induced by ovalbumin (OVA)-alum sensitization and OVA challenge. The concentrations of the Th2-related cytokines IL-4, IL-5, and IL-13 in the bronchial alveolar lavage fluid and the levels of OVA-specific IgE and IgG1 in the serum were lower in mice that received intravenous application of Inf(+)Foxp3+ cells [IV(inf):+(+) group] than in control mice. Some features of allergic airway inflammation were ameliorated by the intravenous application of Inf(-)Foxp3+ cells [IV(inf):+(-) group], but the effects were less distinct than those observed in the IV(inf):+(+) group. We found that Inf(+)Foxp3+ cells migrated to inflammation sites in the lung and expressed higher levels of Treg-cell homing receptors (CCR5 and CCR9) and activation markers (Klrg1, Capg, GARP, Gzmb, OX40) than did Inf(-)Foxp3+ cells.

Conclusion/Significance

T. spiralis infection promotes the proliferation and functional activation of Treg cells. Parasite-induced Treg cells migrate to the inflammation site and suppress immune responses more effectively than non-parasite-induced Treg cells. The adoptive transfer of Inf(+)Foxp3+ cells is an effective method for the treatment and prevention of allergic airway diseases in mice and is a promising therapeutic approach for the treatment of allergic airway diseases.  相似文献   

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TGF-β is widely held to be critical for the maintenance and function of regulatory T (Treg) cells and thus peripheral tolerance. This is highlighted by constitutive ablation of TGF-β receptor (TR) during thymic development in mice, which leads to a lethal autoimmune syndrome. Here we describe that TGF-β–driven peripheral tolerance is not regulated by TGF-β signalling on mature CD4+ T cells. Inducible TR2 ablation specifically on CD4+ T cells did not result in a lethal autoinflammation. Transfer of these TR2-deficient CD4+ T cells to lymphopenic recipients resulted in colitis, but not overt autoimmunity. In contrast, thymic ablation of TR2 in combination with lymphopenia led to lethal multi-organ inflammation. Interestingly, deletion of TR2 on mature CD4+ T cells does not result in the collapse of the Treg cell population as observed in constitutive models. Instead, a pronounced enlargement of both regulatory and effector memory T cell pools was observed. This expansion is cell-intrinsic and seems to be caused by increased T cell receptor sensitivity independently of common gamma chain-dependent cytokine signals. The expression of Foxp3 and other regulatory T cells markers was not dependent on TGF-β signalling and the TR2–deficient Treg cells retained their suppressive function both in vitro and in vivo. In summary, absence of TGF-β signalling on mature CD4+ T cells is not responsible for breakdown of peripheral tolerance, but rather controls homeostasis of mature T cells in adult mice.  相似文献   

18.
There is heterogeneity in invariant natural killer T (iNKT) cells based on the expression of CD4 and the IL-17 receptor B (IL-17RB), a receptor for IL-25 which is a key factor in TH2 immunity. However, the development pathway and precise function of these iNKT cell subtypes remain unknown. IL-17RB+ iNKT cells are present in the thymic CD44+/− NK1.1 population and develop normally even in the absence of IL-15, which is required for maturation and homeostasis of IL-17RB iNKT cells producing IFN-γ. These results suggest that iNKT cells contain at least two subtypes, IL-17RB+ and IL-17RB subsets. The IL-17RB+ iNKT subtypes can be further divided into two subtypes on the basis of CD4 expression both in the thymus and in the periphery. CD4+ IL-17RB+ iNKT cells produce TH2 (IL-13), TH9 (IL-9 and IL-10), and TH17 (IL-17A and IL-22) cytokines in response to IL-25 in an E4BP4-dependent fashion, whereas CD4 IL-17RB+ iNKT cells are a retinoic acid receptor-related orphan receptor (ROR)γt+ subset producing TH17 cytokines upon stimulation with IL-23 in an E4BP4-independent fashion. These IL-17RB+ iNKT cell subtypes are abundantly present in the lung in the steady state and mediate the pathogenesis in virus-induced airway hyperreactivity (AHR). In this study we demonstrated that the IL-17RB+ iNKT cell subsets develop distinct from classical iNKT cell developmental stages in the thymus and play important roles in the pathogenesis of airway diseases.  相似文献   

19.
Surgery is the primary therapeutic strategy for most solid tumours; however, modern oncology has established that neoplasms are frequently systemic diseases. Being however a local treatment, the mechanisms through which surgery plays its systemic role remain unknown. We have investigated the influence of cytoreduction on the immune system of primary and recurrent ovarian cancer. All ovarian cancer patients show an increase in CD4+CD25+FOXP3+ circulating cells (CD4 Treg). CD4/CD8 ratio is increased in primary tumours, but not in recurrent neoplasms. Primary cytoreduction is able to increase circulating CD4 and CD8 effector cells and decrease CD4 naïve T cells. CD4+ Treg cells rapidly decreased after primary tumour debulking, while CD8+CD25+FOXP3+ (CD8 Treg) cells are not detectable in peripheral blood. Similar results on CD4 Treg were observed with chemical debulking in women subjected to neoadjuvant chemotherapy. CD4 and CD8 Treg cells are both present in neoplastic tissue. Interleukin (IL)‐10 serum levels decrease after surgery, while no changes are observed in transforming growth factor‐β1 and IL‐6 levels. Surgically induced reduction of the immunosuppressive environment results in an increased capacity of CD8+ T cells to respond to the recall antigens. None of these changes was observed in patients previously subjected to chemotherapy or affected by recurrent disease. In conclusion, we demonstrate in ovarian cancer that primary debulking is associated with a reduction of circulating Treg and an increase in CD8 T‐cell function. Debulking plays a beneficial systemic effect by reverting immunosuppression and restoring immunological fitness.  相似文献   

20.
Infection of C57BL/6J mice with the parasite Toxoplasma gondii triggers a powerful Th1 immune response that is detrimental to the host. During acute infection, a reduction in CD4+Foxp3+ regulatory T cells (Treg) has been reported. We studied the role of Treg during T. gondii infection by adoptive transfer of cells purified from transgenic Foxp3EGFP mice to infected wild type animals. We found a less severe weight loss, a significant delayed mortality in infected Treg-transferred mice, and reduced pathology of the small intestine that were associated with lower IFN-γ and TNF-α levels. Nevertheless, higher cyst number and parasite load in brain were observed in these mice. Treg-transferred infected mice showed reduced levels of both IFN-γ and TNF-α in sera. A reduced number of CD4+ T cells producing IFN-γ was detected in these mice, while IL-2 producing CD4+ T cells were restored to levels nearly similar to uninfected mice. CD25 and CD69 expression of CD4+ T cells were also down modulated. Our data show that the low Treg cell number are insufficient to modulate the activation of CD4+ T cells and the production of high levels of IFN-γ. Thus, a delicate balance between an optimal immune response and its modulation by Treg cells must exist.  相似文献   

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