首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 601 毫秒
1.
Background The human 5T4 (h5T4) oncofoetal antigen is expressed by a wide variety of human carcinomas including colorectal, ovarian, gastric and renal, but rarely on normal tissues. Its restricted expression on tumour tissues as well as its association with tumour progression and bad prognosis has driven the development of a MVA-based vaccine (TroVax) which has been tested in several early phase clinical trials and these studies have led to the start of a phase III trial in renal cell carcinoma patients. We have recently shown that CD8+ T cells recognizing h5T4 can be generated in the absence of CD4+ T cells from peripheral blood lymphocytes of human healthy individuals. Results We report the existence and expansion of human CD4+ T cells against h5T4 by stimulation with autologous monocyte-derived dendritic cells infected with a replication defective adenovirus encoding the h5T4 cDNA (Ad-h5T4). The h5T4-specific T-cell responses in normal individuals are enhanced by initial depletion of CD25+ cells (putative T regulatory cells) prior to the in vitro stimulation. We have identified a novel h5T4-derived 15-mer peptide recognized by CD4+ T cells in HLA-DR4 positive healthy individuals. Interestingly, CD4+ T cells spontaneously recognizing a different 5T4 epitope restricted by HLA-DR were identified in tumour-infiltrating lymphocytes isolated from a regressing renal cell carcinoma lung metastasis. Conclusion Our data show that CD4+ T cells recognizing h5T4 can be expanded and detected in healthy individuals and a renal cell carcinoma patient. Such h5T4-specific CD4+ T cells boosted or induced by vaccination could act to modulate both cell or antibody mediated anti-tumour responses. This work was supported by Cancer Research UK.  相似文献   

2.
Targeted molecular therapies inhibit proliferation and survival of cancer cells but may also affect immune cells. We have evaluated the effects of Sirolimus and Sorafenib on proliferation and survival of lymphoid cell subsets. Both drugs were cytotoxic to CD4+CD25high T cells, and were growth inhibitory for CD4+ and CD8+ T cells. Cytotoxicity depended on CD3/CD28 stimulation and was detectable within 12 h, with 80–90% of CD4+CD25high cells killed by 72 h. Cell death was due to apoptosis, based on Annexin V and 7AAD staining. Addition of IL-2 prevented the apoptotic response to Sirolimus, potentially accounting for reports that Sirolimus can enhance proliferation of CD4+CD25high cells. These results predict that Sirolimus or Sorafenib would reduce CD4+CD25high cells if administered prior to antigenic stimulation in an immunotherapy protocol. However, administration of IL-2 protects CD4+CD25high T cells from cytotoxic effects of Sirolimus, a response that may be considered in design of therapeutic protocols.  相似文献   

3.
Molecularly defined synthetic vaccines capable of inducing both antibodies and cellular anti-tumor immune responses, in a manner compatible with human delivery, are limited. Few molecules achieve this target without utilizing external immuno-adjuvants. In this study, we explored a self-adjuvanting glyco-lipopeptide (GLP) as a platform for cancer vaccines using as a model MO5, an OVA-expressing mouse B16 melanoma. A prototype B and T cell epitope-based GLP molecule was constructed by synthesizing a chimeric peptide made of a CD8+ T cell epitope, from ovalbumin (OVA257–264) and an universal CD4+ T helper (Th) epitope (PADRE). The resulting CTL–Th peptide backbones was coupled to a carbohydrate B cell epitope based on a regioselectively addressable functionalized templates (RAFT), made of four α-GalNAc molecules at C-terminal. The N terminus of the resulting glycopeptides (GP) was then linked to a palmitic acid moiety (PAM), obviating the need for potentially toxic external immuno-adjuvants. The final prototype OVA-GLP molecule, delivered in adjuvant-free PBS, in mice induced: (1) robust RAFT-specific IgG/IgM that recognized tumor cell lines; (2) local and systemic OVA257–264-specific IFN-γ producing CD8+ T cells; (3) PADRE-specific CD4+ T cells; (4) OVA-GLP vaccination elicited a reduction of tumor size in mice inoculated with syngeneic murine MO5 carcinoma cells and a protection from lethal carcinoma cell challenge; (5) finally, OVA-GLP immunization significantly inhibited the growth of pre-established MO5 tumors. Our results suggest self-adjuvanting glyco-lipopeptide molecules as a platform for B Cell, CD4+, and CD8+ T cell epitopes-based immunotherapeutic cancer vaccines. Both I. Bettahi and G. Dasgupta have contributed equally to this work.  相似文献   

4.
Accumulating evidence suggests that regulatory T cells play a crucial role in preventing autoimmunity. Recently, a naturally occurring CD4+CD25+ T-cell subset that is anergic and also suppressive has been shown to suppress autoimmunity in several animal models. We used proteoglycan-induced arthritis (PGIA) as a study model to investigate the role of the CD4+CD25+ regulatory T cells in autoimmune arthritis. There was no significant change in the percentage of CD4+CD25+ T cells during the immunization period when proteoglycan- or ovalbumin-immunized BALB/c and C57BL/6 mice were compared. An adoptive transfer study showed that the CD4+CD25+ T cells did not protect severe combined immunodeficient mice from arthritis when they were cotransferred with splenocytes from arthritic animals. Similarly, depletion of the CD4+CD25+ T cells did not enhance the onset of the disease or disease severity in severe combined immunodeficient mice. Moreover, CD28-deficient mice, which have very few CD4+CD25+ T cells, were highly resistant to PGIA. These findings indicate that the CD4+CD25+ regulatory T cells may not play a critical role in controlling PGIA.  相似文献   

5.
We have recently provided data suggesting a potential role for mitochondria and Bcl-2-family molecules in apoptosis sensitivity of HIV-specific CD8+ T cells. Here, we report on the role of filamentous (F) actin in this process. Disruption of actin by cytochalasin D (cytD) or lantrunculin A remarkably reduced CD95/Fas-induced apoptosis of HIV-specific CD8+ T cells while their spontaneous apoptosis was unaffected. This inhibition cannot be attributed to changes of CD95/Fas distribution or levels in these cells. Furthermore, cytD treatment reduced CD95/Fas-induced apoptosis of CD8+ T cells from HIV+ patients independently of their differentiation status. CD95/Fas-induced apoptosis of both CD38+ and CD38 HIV-specific CD8+ T cells was inhibited by cytD treatment indicating that actin mediates this apoptotic process independently of the activation level of these cells. CytD was found to reduce the activation of caspase-8 induced by short treatment of purified CD8+ T cells from HIV+ patients with anti-CD95/Fas. Our data reveal actin as a critical mediator of HIV-specific CD8+ T cell apoptosis; further analysis of the molecular mechanisms governing this process may potentially contribute to design new therapies targeting the enhancement of the immune system in HIV infection.  相似文献   

6.
Multiple myeloma (MM) cells produce monoclonal immunoglobulin (Ig) which serves as a truly tumor-specific antigen. The tumor-specific antigenic determinants are localized in the variable (V)-regions of the monoclonal Ig and are called idiotopes (Id). We review here the evidence obtained in a T-cell receptor (TCR) transgenic mouse model that Id-specific, MHC class II–restricted CD4+ T cells play a pivotal role in immunosurveillance and eradication of MHC class II-negative MM cells. In brief, monoclonal Ig secreted by MM cells is endocytosed and processed by antigen-presenting cells (APCs) in the tumor. Such tumor-resident dendritic cell APCs in turn present Id peptide on their class II molecules to Id-specific CD4+ T cells which become activated and indirectly kill the MHC class II-negative myeloma cells. However, if the Id-specific CD4+ cells fail to eliminate the MM cells during their initial encounter, the increasing number of tumor cells secretes so much monoclonal Ig that T-cell tolerance to Id is induced. Extending these findings to MM patients, Id-specific immunotherapy should be applied at a time of minimal residual disease and when new Id-specific T cells have been educated in the thymus, like after high-dose chemotherapy and autologous stem cell transplantation.Abbreviations APC antigen-presenting cell - ASCT autologous stem cell transplantation - CDR complementarity-determining region - CFA complete Freunds adjuvant - DC dendritic cell - GM-CSF granulocyte-macrophage colony-stimulating factor - H heavy - Id idiotope or idiotype - Ig immunoglobulin - IL interleukin - L light - M-component monoclonal component - MGUS monoclonal gammopathy of undetermined significance - MHC major histocompatibility complex - MM multiple myeloma - MOPC mineral oil–induced plasmacytoma - TCR T-cell antigen receptor - V variableA. Corthay and B. Bogen are joint corresponding authors for this article.  相似文献   

7.
Resting naive CD4+CD45R0?CD45RA+ T cells are sensitive to ionomycin. In contrast, resting CD4+CD45RA?CD45R0+ memory T cells show resistance to this Ca2+ ionophore. In the present study, the ability of activated T lymphocytes to respond to ionomycin during the transition from naive precursors into memory T cells has been analyzed. Activated CD4+CD45RA+CD45R0+ T cells are always present both in human peripheral blood (HPB) and in the ionomycin-resistant (IR) fraction. Therefore, some activated T cells are resistant toward the Ca2+ ionophore. CD69 molecules are markers of the very early stage of T cell activation. However, CD4+CD69+ T cells have never been found in the IR fraction. Thus, the majority of CD4+ T lymphocytes at the early stage of activation are ionomycin-sensitive cells. The proportion of CD4+CD25+ T cells did not differ significantly in HPB and in the IR fraction. The presence of CD4+CD25+ T lymphocytes in the IR fraction reflects changes in the Ca2+-signaling pathway at this differentiation step of activated cells. Depending on the expression level of CD25 molecules, the population of CD4+CD25+ cells is divided in T-regulatory (CD25high) and proliferating (CD25low) subpopulations. The action of ionomycin results in a decrease in the portion of the CD4+CD25low T-cells, but it leads to an increase in the proportion of the CD4+CD25high T lymphocytes. Consequently, greater portion of CD4+CD25high T lymphocytes and smaller portion of CD4+CD25low T cells are IR cells. Expression of HLA-DR molecules can be used as the marker for the late activation step. The IR fraction is significantly rich in CD4+HLA-DR+ T lymphocytes in comparison to the blood of the same donor. The link between different differentiation steps of CD4+ T-lymphocytes and alterations in calcium ion homeostasis is discussed.  相似文献   

8.
Various abnormalities in CD4+CD25+ regulatory T cells (Tregs) in systemic lupus erythematosus (SLE) include increased Foxp3+ cells that are CD25 negative. Barring methodological technical factors, these cells could be atypical Tregs or activated non-Treg CD4+ cells that express Foxp3. Two groups have reached opposite conclusions that could possibly reflect the subjects studied. One group studied untreated new-onset SLE and suggested that these T cells were mostly CD25-Foxp3+ non-Tregs. The other group studied patients with long-standing disease and suggested that these cells are mostly dysfunctional Tregs. A third group reported increased Foxp3+CD4+CD25dim rather than CD25- cells in active SLE and these were also non-Tregs. Thus, it is likely that not all Foxp3+ T cells in SLE have protective suppressive activity.  相似文献   

9.
Adoptive transfer of CD4+CD25+ regulatory T cells has been shown to have therapeutic effects in animal models of autoimmune diseases. Chemokines play an important role in the development of autoimmune diseases in animal models and humans. The present study was performed to investigate whether the progression of organ-specific autoimmune diseases could be reduced more markedly by accumulating chemokine receptor-expressing CD4+CD25+ regulatory T cells efficiently in target organs in MRL/MpJ-lpr/lpr (MRL/lpr) mice. CD4+CD25+Foxp3+ T cells (Treg cells) and CD4+CD25+Foxp3+ CCR2-transfected T cells (CCR2-Treg cells) were transferred via retro-orbital injection into 12-week-old MRL/lpr mice at the early stage of pneumonitis and sialadenitis, and the pathological changes were evaluated. Expression of monocyte chemoattractant protein-1 (MCP-1)/CCL2 was observed in the lung and submandibular gland of the mice and increased age-dependently. The level of CCR2 expression and MCP-1 chemotactic activity of CCR2-Treg cells were much higher than those of Treg cells. MRL/lpr mice to which CCR2-Treg cells had been transferred showed significantly reduced progression of pneumonitis and sialadenitis in comparison with MRL/lpr mice that had received Treg cells. This was due to more pronounced migration of CCR2-Treg cells and their localization for a longer time in MCP-1-expressing lung and submandibular gland, resulting in stronger suppressive activity. We prepared chemokine receptor-expressing Treg cells and demonstrated their ability to ameliorate disease progression by accumulating in target organs. This method may provide a new therapeutic approach for organ-specific autoimmune diseases in which the target antigens remain undefined.  相似文献   

10.
Iodine is an essential trace element for thyroid hormone synthesis and metabolism, either low or high intake may lead to thyroid disease, but the pathogenetic mechanisms by which iodine interacts with the thyroid autoimmune are poorly understood. We investigated the dynamic changes of CD4+CD25+ regulatory T cells in NOD.H-2h4 mice with iodine-induced autoimmune thyroiditis (AIT), and explore potential immune mechanism of AIT induced by iodine. NOD.H-2h4 mice were randomly divided into two groups, and received plain water or water containing 0.005% sodium iodide. Eight weeks after iodine provision, the incidences of thyroiditis, relative weights of thyroids, and serum thyroglobulin antibody titers in the iodine-supplied groups were significantly increased compared to the control groups (p < 0.05). The AIT mice had fewer CD4+CD25+Foxp3+ T cells and reduced Foxp3 mRNA expression in splenocytes compared with the controls (p < 0.01), and maintained relatively low levels during the development of thyroiditis. The changes described above aggravated gradually with the extension of iodine treatment. These data suggest that CD4+CD25+ regulatory T cells may be involved in the pathogenesis and development of AIT induced by iodine.  相似文献   

11.

   

CD4+CD25+Foxp3+ regulatory T (Treg) cells are believed to play an important role in suppressing autoimmunity and maintaining peripheral tolerance. How their survival is regulated in the periphery is less clear. Here we show that Treg cells express receptors for gamma chain cytokines and are dependent on an exogenous supply of these cytokines to overcome cytokine withdrawal apoptosis in vitro. This result was validated in vivo by the accumulation of Treg cells in Bim-/- and Bcl-2 tg mice which have arrested cytokine deprivation apoptosis. We also found that CD25 and Foxp3 expression were down-regulated in the absence of these cytokines. CD25+ cells from Scurfy mice do not depend on cytokines for survival demonstrating that Foxp3 increases their dependence on cytokines by suppressing cytokine production in Treg cells. Our study reveals that the survival of Treg cells is strictly dependent on cytokines and cytokine producing cells because they do not produce cytokines. Our study thus, demonstrates that different gamma chain cytokines regulate Treg homeostasis in the periphery by differentially regulating survival and proliferation. These findings may shed light on ways to manipulate Treg cells that could be utilized for their therapeutic applications.  相似文献   

12.
Balnokin YV  Popova LG  Pagis LY  Andreev IM 《Planta》2004,219(2):332-337
Our previous investigations have established that Na+ translocation across the Tetraselmis viridis plasma membrane (PM) mediated by the primary ATP-driven Na+-pump, Na+-ATPase, is accompanied by H+ counter-transport [Y.V. Balnokin et al. (1999) FEBS Lett 462:402–406]. The hypothesis that the Na+-ATPase of T. viridis operates as an Na+/H+ exchanger is tested in the present work. The study of Na+ and H+ transport in PM vesicles isolated from T. viridis demonstrated that the membrane-permeant anion NO3 caused (i) an increase in ATP-driven Na+ uptake by the vesicles, (ii) an increase in (Na++ATP)-dependent vesicle lumen alkalization resulting from H+ efflux out of the vesicles and (iii) dissipation of electrical potential, , generated across the vesicle membrane by the Na+-ATPase. The (Na++ATP)-dependent lumen alkalization was not significantly affected by valinomycin, addition of which in the presence of K+ abolished at the vesicle membrane. The fact that the Na+-ATPase-mediated alkalization of the vesicle lumen is sustained in the absence of the transmembrane is consistent with a primary role of the Na+-ATPase in driving H+ outside the vesicles. The findings allowed us to conclude that the Na+-ATPase of T. viridis directly performs an exchange of Na+ for H+. Since the Na+-ATPase generates electric potential across the vesicle membrane, the transport stoichiometry is mNa+/nH+, where m>n.Abbreviations BTP Bis-Tris-Propane, 1,3-bis[tris(hydroxymethyl)methylamino]-propane - CCCP Carbonyl cyanide m-chlorophenylhydrazone - DTT Dithiothreitol - NCDC 2-Nitro-4-carboxyphenyl N,N-diphenylcarbamate - PMSF Phenylmethylsulfonyl fluoride - PM Plasma membrane  相似文献   

13.
14.
15.
16.
Clonal expansion of CD4+CD28- T cells is a characteristic finding in patients with rheumatoid arthritis (RA). Expanded CD4+ clonotypes are present in the peripheral blood, infiltrate into the joints, and persist for years. CD4+CD28- T cells are oligoclonal lymphocytes that are rare in healthy individuals but are found in high percentages in patients with chronic inflammatory diseases. The size of the peripheral blood CD4+CD28- T-cell compartment was determined in 42 patients with RA and 24 healthy subjects by two-color FACS analysis. The frequency of CD4+CD28- T cells was significantly higher in RA patients than in healthy subjects. Additionally, the number of these cells was significantly higher in patients with extra-articular manifestations and advanced joint destruction than in patients with limited joint manifestations. The results suggest that the frequency of CD4+CD28- T cells may be a marker correlating with extra-articular manifestations and joint involvement.  相似文献   

17.
CD25+CD4+ regulatory T cells participate in the regulation of immune responses. We recently demonstrated the presence of CD25brightCD4+ regulatory T cells with a capacity to control T cell proliferation in the joints of patients with rheumatoid arthritis. Here, we investigate a possible accumulation of these regulatory T cells in the inflamed joint of different rheumatic diseases including rheumatoid arthritis. The studies are also extended to analyze whether cytokine production can be suppressed by the regulatory T cells. Synovial fluid and peripheral blood samples were obtained during relapse from 36 patients with spondyloarthropathies, 21 adults with juvenile idiopathic arthritis and 135 patients with rheumatoid arthritis, and the frequency of CD25brightCD4+ T cells was determined. Of 192 patients, 182 demonstrated a higher frequency of CD25brightCD4+ T cells in synovial fluid than in peripheral blood. In comparison with healthy subjects, the patients had significantly fewer CD25brightCD4+ T cells in peripheral blood. For functional studies, synovial fluid cells from eight patients were sorted by flow cytometry, and the suppressive capacity of the CD25brightCD4+ T cells was determined in in vitro cocultures. The CD25brightCD4+ T cells suppressed the production of both type 1 and 2 cytokines including interleukin-17, as well as proliferation, independently of diagnosis. Thus, irrespective of the inflammatory joint disease investigated, CD25brightCD4+ T cells were reduced in peripheral blood and enriched in the joint, suggesting an active recruitment of regulatory T cells to the affected joint. Their capacity to suppress both proliferation and cytokine secretion might contribute to a dampening of local inflammatory processes.  相似文献   

18.
Tacrolimus is a widely used T cell targeted immunosuppressive drug, known as a calcineurin inhibitor. However, the exact pharmacological effects of tacrolimus on CD4+ T cells have yet to be elucidated. This study investigated the effects of tacrolimus on CD4+ T cell subsets. Mouse or human CD4+ T cells were cultured with immobilized anti-CD3/CD28 antibodies in the presence of tacrolimus. The cell division of CD4+ T cells was analyzed using a flow cytometer according to the expression of Foxp3. The gene expression patterns of tacrolimus-exposed T cells were examined by quantitative PCR. In the case of conventional CD4+ T cells (Tconv cells), tacrolimus inhibited T cell receptor stimulation-induced cell division. In contrast, the cell division of regulatory CD4+ T cells (Treg cells) was even promoted in the presence of tacrolimus, especially in humans. Tacrolimus did not promote conversion of Tconv to Treg cells in mice. Furthermore, tacrolimus modified the expression levels of Foxp3-regulated T cell receptor signal related-genes, PTPN22 and Itk, in human Treg cells. Immunosuppressive effect of tacrolimus may be attributed to the relatively enhanced proliferation of Treg cells in association with altered gene expression levels of TCR signaling molecules.  相似文献   

19.
This study addresses the mechanisms of oxygen-induced regulation of ion transport pathways in mouse erythrocyte, specifically focusing on the role of cellular redox state and ATP levels. Mouse erythrocytes possess Na+/K+ pump, K+-Cl and Na+-K+-2Cl cotransporters that have been shown to be potential targets of oxygen. The activity of neither cotransporter changed in response to hypoxia-reoxygenation. In contrast, the Na+/K+ pump responded to hypoxic treatment with reversible inhibition. Hypoxia-induced inhibition was abolished in Na+-loaded cells, revealing no effect of O2 on the maximal operation rate of the pump. Notably, the inhibitory effect of hypoxia was not followed by changes in cellular ATP levels. Hypoxic exposure did, however, lead to a rapid increase in cellular glutathione (GSH) levels. Decreasing GSH to normoxic levels under hypoxic conditions abolished hypoxia-induced inhibition of the pump. Furthermore, GSH added to the incubation medium was able to mimic hypoxia-induced inhibition. Taken together these data suggest a pivotal role of intracellular GSH in oxygen-induced modulation of the Na+/K+ pump activity.  相似文献   

20.
During the antigen-dependant activation process several subsets CD8+ T cells appear with different phenotypic and functional characteristics. Recent studies indicate that the state of T cell differentiation radically affects their ability to effectively respond to tumor challenge, with early effector CD8+ T (CD62Lhigh) cells having better anti-tumor activity. Thus strategies aimed at optimizing the generation of such subpopulations could significantly enhance the effectiveness of adoptive cell therapy (ACT) for cancer. In this study, we show that priming of naïve CD8+ T cells in the presence of IL-12 selectively rescued early CD8+ CD62Lhi from activation induced cell death and resulted in the increased accumulation of this subset of CD8+ T cells. Furthermore, we demonstrated that IL-12 directly modulated the expression of CD62L on activated CD8+ T cells. When used for ACT, naïve CD8+ T cells primed in vitro in the presence of IL-12 showed superior anti-tumor activity toward B16 melanoma. Importantly, using the Pmel-1 model, priming pmel-1 cells in vitro with IL-12 reduced the state of functional tolerance associated with the non-mutated “self” tumor antigen gp100, as demonstrated by significant tumor responses in the absence of vaccination. Together, our results suggest that in vitro conditioning of naïve CD8+ T cells with IL-12 prior to ACT could significantly enhance their anti-tumor activity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号