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Increases in numbers or activities of regulatory T lymphocytes (Tregs) have been linked to the establishments of several persistent infections. It has been previously shown that porcine reproductive and respiratory syndrome virus (PRRSV) can negatively modulate the host immune responses, resulting in persistent infection and secondary immunodeficiency. Recently, the existence of porcine CD4+CD25+ Tregs has been demonstrated. We investigated the effect of PRRSV on the CD4+CD25+ Tregs. The CD4+CD25+Foxp3+ T lymphocytes in the peripheral blood mononuclear cells (PBMCs) were identified, using the anti-human anti-Foxp3 monoclonal antibody. In vitro culture of porcine PBMC in the presence of PRRSV, but not classical swine fever virus, significantly increased the numbers of Foxp3+ lymphocytes, particularly in the CD4+CD25high subpopulation. The time-course study revealed that PRRSV significantly increased the numbers of viral-specific CD4+CD25highFoxp3+ subpopulation in the culture starting from 12 h through the end of the observation period. Consistent to the results obtained by flow cytometry, enhanced Foxp3 gene expression was observed in the PBMC cultured with PRRSV in a time-course manner. The presence of monocyte-derived DC in the co-culture significantly enhanced the induction of CD4+CD25+ Foxp3+ T lymphocytes. The PRRSV-induced CD4+CD25high T lymphocytes exhibited suppressive activity when co-cultured with PHA-activated, autologous peripheral blood leukocytes, indicating the suppressive activity of the PRRSV-specific Tregs. In addition, PRRSV exposure significantly increased the numbers of PRRSV-specific CD4+CD25+Foxp3+ subpopulation in the PBMC of infected pigs at 10 days post-infection. In summary, the results indicated that PRRSV could increase the numbers of viral-specific, inducible regulatory T lymphocytes in the porcine PBMC, both in vitro and in vivo. The findings suggested the novel immunomodulatory mechanism induced by PRRSV.  相似文献   

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This paper investigates the in vitro effect of dexamethasone on bovine CD25(high)CD4(+), CD25(low)CD4(+) and CD25(-)CD4(+) T cells. Only a small percentage of bovine CD25(high)CD4(+) (2-4%) and CD25(low)CD4(+) (1-2%) cells expressed Foxp3. Dexamethasone caused considerable loss of CD25(-)CD4(+) cells, but it increased the relative and absolute numbers of CD25(high)CD4(+) and CD25(low)CD4(+) lymphocytes, while at the same time reducing the percentage of Foxp3(+) cells within the latter subpopulations. Considering all these, as well as the intrinsically poor Foxp3 expression in bovine CD25(+)CD4(+), it can be concluded that the drug most probably increased the number of activated non-regulatory CD4(+) lymphocytes. It has been found that changes in cell number were at least partly caused by proapoptotic effect of the drug on CD25(-)CD4(+) cells and antiapoptotic effect on CD25(high)CD4(+) and CD25(low)CD4(+) cells. The results obtained from this study indicate that the involvement of CD4(+) lymphocytes in producing the anti-inflammatory and immunosuppressive effect of dexamethasone in cattle results from the fact that the drug had a depressive effect on the production of IFN-γ by CD25(-)CD4(+) cells. Secretion of TGF-β and IL-10 by CD4(+) lymphocytes was not involved in producing these pharmacological effects, because the drug did not affect production of TGF-β and, paradoxically, it reduced the percentage of IL-10(+)CD4(+) cells.  相似文献   

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Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis caused by bites of midges from the genus Culicoides. We have shown previously that peripheral blood mononuclear cells (PBMC) from IBH-affected horses produce higher levels of IL-4 and lower levels of IL-10 and TGF-β1 than those from healthy horses, suggesting that IBH is associated with a reduced regulatory immune response. FoxP3 is a crucial marker of regulatory T cells (Tregs). Here we have determined the proportion of CD4(+)CD25(+)FoxP3(+) T cells by flow cytometry in PBMC directly after isolation or after stimulation with Culicoides extract or a control antigen (Tetanus Toxoid). There were no differences between healthy and IBH horses either in the proportion of FoxP3(+)CD4(+)CD25(+) cells in freshly isolated PBMC or in the following stimulation with Tetanus Toxoid. However, upon stimulation of PBMC with the allergen, expression of FoxP3 by CD4(+)CD25(+high) and CD4(+)CD25(+dim) cells was significantly higher in healthy than in IBH horses. Addition of recombinant IL-4 to PBMC from healthy horses stimulated with the allergen significantly decreased the proportion of FoxP3 expressing cells within CD4(+)CD25(+high). These results suggest that IBH is associated with a decreased number of allergen-induced Tregs. This could be a consequence of the increased IL-4 production by PBMC of IBH-affected horses.  相似文献   

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Several distinct T lymphocyte subpopulations with immunoregulatory activity have been described in a number of mammalian species. This study performed a phenotypic analysis of cells expressing regulatory T cell (Treg) markers in the peripheral blood of a cohort of 18 horses aged 6 months to 23 years, using antibodies to both intracellular and cell surface markers, including Forkhead box P3 (FOXP3), CD4, CD8, CD25, interferon gamma (IFNγ) and interleukin 10 (IL-10). In peripheral blood, a mean of 2.2 ± 0.2% CD4+ and 0.5 ± 0.1% CD8+ lymphocytes expressed FOXP3. The mean percentage of CD4+FOXP3+ cells was found to be significantly decreased in horses 15 years and older (1.5%) as compared to horses 6 years and younger (2.7%), but did not differ between females and males and ponies and horses. Activation of peripheral blood mononuclear cells by pokeweed mitogen resulted in induction of CD25 and FOXP3 expression by CD4+ cells, with peak expression noted after 48 and 72 h in culture respectively. Activated CD4+FOXP3+ cells expressed IFNγ (35% of FOXP3+ cells) or IL-10 (9% FOXP3+ cells). Cell sorting was performed to determine FOXP3 expression by CD4(+)CD25(-), CD4(+)CD25(dim) and CD4(+)CD25(high) subpopulations. Immediately following sorting, the percentage of CD4+FOXP3+ cells was higher within the CD4(+)CD25(high) population (22.7-26.3%) compared with the CD4(+)CD25(dim) (17% cells) but was similar within the CD4(+)CD25(dim) and CD4(+)CD25(high) cells after resting in IL-2 (9-14%). Fewer than 2% of cells in the CD4(+)CD25(-) population expressed FOXP3. These results demonstrate heterogeneity in equine lymphocyte subsets that express molecules associated with regulatory T cells. CD4+FOXP3+ cells are likely to represent natural Tregs, with CD4+FOXP3+IL-10+ cells representing either activated natural Tregs or inducible Tregs, and CD4+FOXP3+IFNγ+ cells likely to represent activated Th1 cells.  相似文献   

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A dual expressing (CD4(+)/CD8(+)) porcine lymphoblastoid T-cell line (pIL-2d) generated from peripheral blood mononuclear (MN) cells shown to be highly responsive to exogenous interleukin-2 (IL-2) was characterized. The swine MN cells were initially stimulated with concanavalin A (Con A), and sub-passaged using decreasing amounts of conditioned medium (CM), which was prepared from culture fluids of Con A activated porcine MN cells, until a steady growth was observed. The resulting pIL-2d cells require exogenous IL-2 from CM and are highly responsive to recombinant human IL-2 (rhIL-2). The pIL-2d cells exhibited a specific, dose-dependent proliferative response to stimulation with IL-2. The specificity of this proliferative response was confirmed to be IL-2 induced by its inhibition with an anti-swine IL-2 receptor (alpha-swIL-2R) monoclonal antibody (mAb). Furthermore, the pIL-2d cells are highly responsive to exogenous IL-2 contained in culture fluids derived from antigen-driven blastogenic tests performed with lymphocytes of vaccinated swine. This property makes the pIL-2d cells an ideal functional adjunct to immunochemical or molecular tests that are commonly used to measure total porcine IL-2. Interestingly, the phenotype of the pIL-2d cells after five or more passages was shown by flow cytometric analysis to be CD4(+)/CD8(+)/CD45RA(-)/CD25(+) and to remain unchanged thereafter. Although, the mechanism of selection and maintenance of the CD4(+)/CD8(+) DP cells developed here remains unclear, our data suggest that an oligoclonal or polyclonal expansion and maintenance of cells of this phenotype was mediated by exogenous IL-2.  相似文献   

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Thymic CD4(+)CD25(+) cells from ducks were characterized for mammalian T regulatory cells' suppressive and cytokine production properties. The cross reactivity of anti-chicken CD25 monoclonal antibody with duck CD25 was confirmed by evaluating Concanavalin-A-stimulated CD25 upregulation in splenocytes. CD4(+)CD25(+) cells were detectable in the thymus, spleen, cecal tonsil, and lung (airsacs), but not in the bursa. Duck CD4(+)CD25(+) cells had approximately nine-fold higher IL-10 mRNA, 12-fold higher TGF-β, 16-fold higher CTLA-4, and nine-fold higher LAG-3 mRNA amounts than thymic CD4(+)CD25(-) cells. Thymic CD4(+)CD25(+) cells had no detectable levels of IL-2 mRNA. Duck CD4(+)CD25(+) cells had a three-fold higher IL-10 mRNA amount than chicken CD4(+)CD25(+) cells. Duck CD4(+)CD25(+) cells were anergic in vitro. Duck CD4(+)CD25(+) cells suppressed naive cell proliferation at effector: responder cell ratios above 0.5:1 in both contact-dependent and -independent pathways. It could be concluded that thymic CD4(+)CD25(+) cells in ducks are most likely the counterpart of mammalian T regulatory cells.  相似文献   

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Surface expression of IL-2R-alpha (CD25) is widely used to identify activated lymphocyte populations, while interferon-gamma (IFN-gamma) levels have been shown to be a good indicator of cell-mediated immunity (CMI) in pigs. To investigate the relationship between these two parameters, we developed an intracellular cytokine-staining assay and studied the kinetics of cytokine (IFN-gamma and interleukin-10, IL-10) production relative to CD25 expression in porcine lymphocyte subpopulations, following immunization with a classical swine fever (CSF) vaccine. The number of activated memory T cells (CD4(+)CD8(+)CD25(+) cells) increased slightly in the peripheral blood mononuclear cell (PBMC) population soon after vaccination, then diminished within a few weeks. The number of activated cytotoxic T cells (CD4(-)CD8(+)CD25(+) cells) peaked approximately 2 weeks after the memory population. Although the number of IFN-gamma producing cells detected in this experiment was relatively low, the CD4(+)CD8(+) T cells were major IFN-gamma producers in the PBMCs throughout the experiment. In another experiment, CSF-vaccinated pigs were challenged with a virulent classical swine fever virus (CSFV), and the kinetics of CD25 expression and cytokine productions were monitored. Following exposure to the virus, the number of IFN-gamma producing cells in the PBMCs increased markedly in both the vaccinated and unvaccinated groups. The CD4(-)CD8(+) cells were major IFN-gamma producing cells in vaccinated pigs, while both CD4(+)CD8(+) and CD4(-)CD8(+) populations contributed to the IFN-gamma production in the control group. Interestingly, the enhanced IFN-gamma production was not associated with the upregulation of CD25 expression following the CSFV challenge. In addition, exposure to the virulent CSFV significantly increased interleukin-10 production by the CD4(-)CD8(+) populations in PBMCs of the unvaccinated pigs. Taken together, our results indicated that CD25 expression and IFN-gamma production were not tightly associated in porcine lymphocytes. In addition, the CD4(-)CD8(+) lymphocytes of the PBMCs played a major role in cytokine productions following the CSFV challenge.  相似文献   

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In chickens, thymic CD4(+)CD25(+) cells are characterized as regulatory T cells. The objectives of this experiment were to study the effects of an in vivo lipopolysaccharide (LPS) injection on the percentage of CD4(+)CD25(+) cells in peripheral organs and the suppressive properties of splenic CD4(+)CD25(+) cells in chickens. Chickens were injected with LPS and CD4(+)CD25(+) cells were analyzed at 1, 2, 3, 5, and 10 d post LPS injection. The LPS injection increased CD4(+)CD25(+) cell percentage approximately 5-fold in the blood at 1 d post LPS injection (P < 0.001), 3-fold in the thymus at 3 d post LPS injection (P = 0.001), and 2.5-fold in the spleen at 2 d post LPS injection (P = 0.001) compared with the no-LPS-injected group. The LPS injection did not alter the CD4(+)CD25(+) cell percentage in the cecal tonsil (P = 0.162), lung (P = 0.098), or bone marrow (P = 0.071) at any time point measured. At 2 d post LPS injection, splenic CD4(+)CD25(+) cells lost their suppressive ability (P < 0.001). At 5 d post LPS injection, splenic CD4(+)CD25(+) cells not only regained their suppressive ability, but also became supersuppressive (P < 0.001). Splenic CD4(+)CD25(+) cells at 5 d post LPS injection produced 5.5-fold more (P = 0.005) IL-10 mRNA than splenic CD4(+)CD25(+) cells at 0 and 2 d post LPS injection. In conclusion, chicken regulatory T cells are differentially activated to facilitate immune response during the early stage of inflammation and to facilitate immune suppression at a later stage of inflammation.  相似文献   

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Extrathymic CD4/CD8 double positive T cells   总被引:6,自引:0,他引:6  
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Feline immunodeficiency virus (FIV) infection leads to hypergammaglobulinemia through mechanisms that remain poorly understood. We investigated changes in plasma globulin level, B cells, and T cells with progression of the clinical stage of FIV-infected cats. We classified FIV-infected cats into the stage of Asymptomatic carrier (AC) and AIDS-related complex (ARC) based on the clinical symptoms, and measured the plasma globulin level, the CD4(+) T-cell counts, and analyzed surface markers of B cells. We investigated the relationship between the plasma globulin level and regulatory T cells (Tregs) using the Forkhead box P3 (FOXP3) mRNA expression level. In FIV-infected cats, the plasma globulin level and the surface immunoglobulin (sIg)(+) CD21(-) B-cell counts were increased, whereas the CD4(+) T-cell counts were decreased compared with specific-pathogen free (SPF) cats. The mRNA expression of Blimp-1 (master gene of plasma cells) was increased in peripheral blood, and the FOXP3 mRNA expression level was decreased in CD4(+) T-cells. These immunological changes were marked in the ARC stage. These data indicate that the decrease of Tregs and the increase of plasma cells lead to hypergammaglobulinemia.  相似文献   

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Evaluation of the changes induced by immunological interventions requires a baseline against which to compare those changes. The age-related changes in the CD8(+) T-cell population of cattle were studied. The results indicate that CD8(+) T-cells could be divided into γ/δ TCR1(+) and γ/δ TCR1(-) according to their expression of the γ/δ T-cell receptor. As a proportion, the CD8(+) γ/δ TCR1(+) population appears to increase with age. Within the CD8(+)γ/δ TCR1(-) a population of cells expressing a profile of surface molecules previously associated with effector memory T cells (CD45RO(+), CD62L(-), CD27(-), CD45RA(-) and CD28(-)) increases with age. Furthermore, a parallel increase with age in the proportion of CD8(+)CD45RO(+) T cells that express the cytotoxic granule protein perforin was observed. In peripheral tissues, namely lungs, it was found that the majority of CD8(+) T cells present expressed a phenotype indicative of previously primed T cells (high expression of CD45RO and perforin). In contrast, only a small population of memory CD8(+) T cells was present in lymphoid tissue where most of the CD8(+) T cells expressed a na?ve phenotype. In conclusion, in cattle, like in human, CD8(+) T cells that express a phenotype associated with antigen experience accumulate with age that may play a role in immunocompetence as the individual ages.  相似文献   

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In dogs a CD4(+)CD8(+) double positive T cell subpopulation exists that has not been phenotypically defined yet. We demonstrate that canine CD4(+)CD8(+) T cells are mature CD1a(-) and TCRαβ(+) T cells. To analyse the activation potential of CD4(+)CD8(+) T cells, PBMC from dogs vaccinated against canine distemper virus (CDV) were re-stimulated with CDV. Upon antigen-specific stimulation, the CD4(+)CD8(+) T cell fraction increases and consists nearly exclusively of proliferated cells. Similarly, other features of activated effector/memory T cells such as up-regulation of CD25 and MHC-II as well as down-regulation of CD62L (L-selectin) were observed in CD4(+)CD8(+) T cells after stimulation. Canine CD4(+)CD8(+) T cells are less abundant, but more heterogeneous than porcine ones, comprising a small proportion expressing the β chain of CD8 in addition to the CD8α chain, like human CD4(+)CD8(+) T cells. In summary, this analysis provides the basis for functional characterisation of the in vivo relevance of CD4(+)CD8(+) T cells in T-cell mediated immunity.  相似文献   

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Regulatory T cells (Tregs) play a critical role in the maintenance of the host's immune system. Tregs, particularly CD4+CD25+Foxp3+ T cells, have been reported to be involved in the immune evasion mechanism of tumors and several pathogens that cause chronic infections. Recent studies showed that a Treg-associated marker, cytotoxic T-lymphocyte antigen 4 (CTLA-4), is closely associated with the progression of several diseases. We recently reported that the proportion of Foxp3+CD4+ cells was positively correlated with the number of lymphocytes, virus titer, and virus load but inversely correlated with IFN-γ expression in cattle infected with bovine leukemia virus (BLV), which causes chronic infection and lymphoma in its host. Here the kinetics of CTLA-4+ cells were analyzed in BLV-infected cattle. CTLA-4 mRNA was predominantly expressed in CD4+ T cells in BLV-infected cattle, and the expression was positively correlated with Foxp3 mRNA expression. To test for differences in the protein expression level of CTLA-4, we measured the proportion of CTLA-4-expressing cells by flow cytometry. In cattle with persistent lymphocytosis (PL), mean fluorescence intensities (MFIs) of CTLA-4 on CD4+ and CD25+ T cells were significantly increased compared with that in control and aleukemic (AL) cattle. The percentage of CTLA-4+ cells in the CD4+ T cell subpopulation was positively correlated with TGF-β mRNA expression, suggesting that CD4+CTLA-4+ T cells have a potentially immunosuppressive function in BLV infection. In the limited number of cattle that were tested, the anti-CTLA-4 antibody enhanced the expression of CD69, IL-2, and IFN-γ mRNA in anti-programmed death ligand 1 (PD-L1) antibody-treated peripheral blood mononuclear cells from BLV-infected cattle. Together with previous findings, the present results indicate that Tregs may be involved in the inhibition of T cell function during BLV infection.  相似文献   

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WC1+ cells in cattle exhibit both regulatory and effector activities. However, it has not been elucidated whether they are so plastic that both activities co-exist in one cell or there are separate subpopulations of effector and regulatory cells. Since the production of IFN-gamma and IL-10 seems to be related to WC1+ cells' effector and regulatory function, respectively, the main aim of this study was to determine whether those cytokines are produced by separate subpopulations of WC1+, or are co-produced by the same cells. Due to increasingly frequent emphasised role of consumption of IL-2 in the mechanism of suppressor action of mouse CD25+CD4+ T regulatory cells, expression of the receptor's alpha chain for interleukin 2 (CD25) on WC1+ lymphocytes has been evaluated. An average of 5.21% of WC1+ cells obtained from PBMCs of 12-month-old heifers show constitutive expression of the CD25 molecule, with CD25(high)WC1+ and CD25(low)WC1+ cells accounting for 1.05% and 4.10% of WC1+ lymphocytes, respectively. For detection of intracellular cytokine production, PBMCs were stimulated with concanavalin A. Both IFN-gamma(-) and IL-10-producing cells within the CD25(-)WC1+ and CD25+WC1+ subpopulations were mainly separate subpopulations. The average percentage of IFN-gamma(+)IL-10(-), IFN-gamma(-)IL-10+ and IFN-gamma(+)IL-10+ cells among CD25(-)WC1+ lymphocytes was 4.03%, 2.67% and 0.51%, respectively. A positive correlation was observed between the presence of the CD25 molecule on WC1+ lymphocytes and production of IL-10 and TGF-beta, because the average percentage of IFN-gamma(-)IL-10+ and IFN-gamma(+)IL-10+ among CD25+WC1+ lymphocytes was 3 and 4.5 times higher as compared to the corresponding cells in the CD25(-)WC1+ subpopulation, whereas the percentage of IFN-gamma(+)IL-10(-) cells in both the subpopulations was not significantly different. The percentage of TGF-beta+ cells within the CD25+WC1+ subpopulation was 2.72 times as high as that of CD25(-)WC1+ lymphocytes. Therefore, with respect to the production of IFN-gamma, IL-10 and TGF-beta, CD25+WC1+ lymphocytes turn out to have a more suppressor profile than CD25(-)WC1+.  相似文献   

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