负性协同刺激分子B7-H4在小鼠树突状细胞上的表达及其生物学意义

目的 探讨B7-H4分子在小鼠树突状细胞分化发育过程中的表达及其在T细胞活化中的作用.方法 采用GM-CSF和IL-4联合方案体外诱导小鼠髓系树突状细胞(DCs);采用流式细胞术检测未成熟DCs、成熟DCs以及IL-10诱导的DCs表面B7-H4分子的表达;采用3H-TdR掺入试验和抗B7-H4单抗(McAb)阻断试验分析DCs表达的B7-H4分子对T淋巴细胞的共刺激效应.结果 经GM-CSF和IL-4联合方案体外诱导的未成熟DCs较高水平表达B7-H4,在IL-10作用下B7-H4表达进一步上调,经TNF-α刺激成熟后,B7-H4的表达显著下调,不同功能状态下DCs表面B7-H4分子均可抑制T细胞的增殖,但以未成熟DCs、IL-10诱导的DCs表面B7-H4分子的抑制作用更为显著.结论 不同功能状态下的DCs均有B7-H4分子的表达,处于抑制状态下的DCs通过高表达B7-H4介导免疫不应答效应.     

人外周血单核细胞来源树突状细胞的成熟诱导

目的：探讨诱导树突状细胞成熟的最优方法。方法：以细胞因子GM-CSF和IL-4体外诱导人单核细胞来源的树突状细胞，分别采用CD40L、LPS、TNF-α、细胞因子鸡尾酒法（TNF-α、IL-6、IL-1β、PGE2）诱导成熟，24小时后收获DCs以流式细胞仪检测其成熟表型CD80、CD83、CD86、HLA-DR和FITC-Dextran的内吞能力，ELISA法检测其IL-12的分泌，MTT法检测其刺激淋巴细胞增殖活性。结果：CD40L、LPS、TNF-α、鸡尾酒法均可诱导DCs的成熟，其中以鸡尾酒法诱导成熟的效果最优，CD83的表达率为66.91%（P〈0.05）；成熟DCsFITC-Dextran的内吞能力明显下降；成熟DCsIL-12分泌量明显高于未成熟DCs，其中鸡尾酒法诱导成熟的DCs的IL-12分泌量最高，成熟的DCs有较强的刺激淋巴细胞增殖能力。结论：细胞因子鸡尾酒法是诱导DCs成熟的最佳方法。     

小鼠树突状细胞表面PD-L1分子对T淋巴细胞协同刺激效应的研究

目的：琛讨小鼠髓系DCs表面PD-L1分子在树突状细胞介导T细胞免疫应答中的作用。方法：采用流式细胞术分别检测未成熟DCs和凋亡肿瘤细胞负载并经CD40配基化的成熟DCs表面免疫分子的表达；混合淋巴细胞反应(MLR)和抗PD-L1单抗阻断试验分析未成熟DCs和成熟DCs表达的PD-L1分子对T淋巴细胞的协同刺激／抑制效应；^3H-TdR掺入试验检测未成熟DCs和成熟DCs对T淋巴细胞的促增殖效应；ELISA测定各组MLR反应上清中IL-10、IFN-γ的分泌水平；MTT比色法检测成熟DCs激发的肿瘤抗原特异性CTL对肿瘤细胞的杀伤效应。结果：未成熟DCs表面高表达PD-L1，负性调节未成熟DCs对自体T淋巴细胞的促增殖作用，抑制T细胞分泌IL-10、IFN-γ；凋亡肿瘤细胞负载并经CD40配基化的成熟DCs中等水平表达PD-L1，具有显著增强对自体T细胞的体外激发、扩增和细胞毒效应的作用，并可增加T细胞的IFN-γ分泌。结论：未成熟DCs高表达PD-L1抑制了对T细胞共刺激效应；CD40配基化成熟的DCs中度表达。PD-L1有助于激发T细胞介导免疫应答。     

TRAF6在人PBMC来源的树突状细胞成熟中的作用

目的: 探讨肿瘤坏死因子受体相关因子6(TRAF6)在不同成熟度树突状细胞(DCs)中的表达及其对DCs免疫刺激活性的影响。方法: 重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)和重组人白细胞介素4(IL-4)体外诱导的人外周血单个核细胞来源的DCs,经TNF-α、LPS和细胞因子鸡尾酒法诱导成熟,分别以流式细胞术、ELISA和混合淋巴细胞反应(MLR)检测DCs的表面标志、IL-12分泌和刺激淋巴细胞增殖能力。Western blotting和real-time PCR分别检测各组TRAF6蛋白水平及mRNA的表达。结果: 各组DCs均表达TRAF6,成熟状态最佳的鸡尾酒诱导下DCs的TRAF6蛋白表达最高。高表达TRAF6的DCs可促进IL-12的分泌,增强刺激淋巴细胞增殖的能力。结论: TRAF6是调节DCs激活和成熟的关键因素。     

补体C5b-9复合物促进树突状细胞成熟

探讨补体C5b-9复合物对树突状细胞成熟及免疫学功能的影响。rhGM-CSF+rhIL-4体外诱导单核细胞分化为不成熟树突状细胞,体外于不成熟树突状细胞表面用补体蛋白纯品组装CSb-9,37℃,5%CO_2温育96 h,流式分析细胞表型及抗原捕获能力;与同种异体CD4~+和CD8~+T细胞共培养检测其免疫刺激功能;ELISA检测细胞因子分泌。结果显示,亚溶解型C5b-9处理DC表面标志CD83、HLA、CD80、CD86、B7-H1、B7-H3、B7-H4以及BTLA等表达上调;DC分泌IL-12及TNF-α上调,抗原捕获能力降低;C5b-9处理DC刺激CD4~+T细胞活化及分泌IFN-γ、IL-2能力增强。结论:补体C5b-9复合物可以促进树突状细胞成熟,衔接天然免疫和特异性免疫。     

吞噬自身抗原对骨髓来源树突状细胞体外分化发育及功能的影响

目的:观察小鼠骨髓来源树突状细胞吞噬自身抗原后体外分化发育及功能的变化,研究其对免疫状态的影响.方法:小鼠骨髓细胞经GM-CSF+IL-4诱导分化为DCs,采用荧光显微镜和流式细胞仪检测DCs的纯度;运用免疫组化法及透射电镜鉴定DCs能否吞噬自身抗原;流式细胞仪检测吞噬自身抗原后DCs的CD86、MHCⅡ的变化; MTT法检测吞噬自身抗原后DCs刺激同基因背景小鼠脾淋巴细胞增殖能力的改变;ELISA法检测脾淋巴细胞经DCs刺激后,分泌IL-4、IFN-γ量的改变.结果:所培养DCs的纯度为90.6%,DCs能够吞噬自身抗原,吞噬自身抗原后的DCs体外分化发育异常,抑制同基因背景小鼠脾淋巴细胞的增殖,刺激同基因背景小鼠脾淋巴细胞分泌IL-4增加,分泌IFN-γ减少.结论:DCs吞噬自身抗原后能够抑制自身成熟,促进淋巴细胞免疫耐受,促进体液免疫.     

Lewis大鼠骨髓来源成熟和未成熟树突状细胞的提取与鉴别

背景：树突状细胞在未成熟阶段表现出极强的抗原吞噬功能，它可以在免疫耐受、癌症的免疫治疗等方面都表现出极大的优越性。但由于未成熟树突状细胞在生物体内含量极微，这就严重限制了它在临床、科研方面的应用。目的：提取鉴别Lewis大鼠骨髓来源成熟和未成熟树突状细胞。方法：从Lewis大鼠骨髓中分离骨髓前体细胞，应用20 ng/m L粒细胞集落刺激因子、10 ng/m L白细胞介素4培养7 d诱导为未成熟树突状细胞，然后在未成熟树突状细胞中加入1μg/m L脂多糖继续培养2 d诱导为成熟树突状细胞。采用荧光倒置显微镜观察树突状细胞形态，流式细胞仪鉴定成熟和未成熟树突状细胞表面特异性分子，ELISA检测成熟和未成熟树突状细胞培养上清白细胞介素10、白细胞介素12和白细胞介素17A因子的分泌水平，混合淋巴细胞反应检测成熟和未成熟树突状细胞对T淋巴细胞的刺激反应。结果与结论：(1)普通荧光倒置显微镜下观察树突状细胞具有明显的突起结构；(2)流式细胞仪可见未成熟树突状细胞低表达CD40、CD86等共刺激分子；相反，成熟树突状细胞高表达上述共刺激分子；(3)未成熟树突状细胞的白细胞介素10、白细胞介素17A...     

丁酸钠诱导的未成熟树突状细胞的免疫学功能研究

目的： 探讨丁酸钠对人外周血来源的树突状细胞（DC）的成熟状态和免疫学功能的影响。方法： 通过粒细胞－巨噬细胞集落刺激因子（GM-CSF）和白细胞介素4（IL-4）结合丁酸钠体外诱导人外周血来源的DC，6 d后结合不同成熟因子诱导成熟，并以流式细胞仪、FITC标记的Dextran的内吞检测、混合淋巴细胞反应（MLR）、ELISA法分别检测DC的表面标志、内吞能力、DC刺激淋巴细胞增殖能力和白细胞介素12（IL-12）分泌量的改变。结果： 丁酸钠可以抑制DC成熟，使DC具有较强的抗原吞噬能力，而刺激淋巴细胞增殖能力和IL-12的分泌能力下降。结论： 丁酸钠可以抑制DC成熟，诱导不成熟DC生成，在移植免疫耐受方面具有较好的应用前景。     

BTLA-HVEM通路阻断对树突状细胞功能影响的体内外研究

目的 探讨阻断BTLA-HVEM(B/T淋巴细胞弱化因子疱疹病毒进入介质)通路对树突状细胞功能的影响和相关免疫学机制.方法 构建小鼠BTLA胞外功能区的真核表达载体psBTLA,转染CHO细胞;HSP70-TC-1肿瘤抗原肽刺激小鼠骨髓来源DCs,流式细胞仪检测处理后DCs表面BTLA、HVEM的表达,同时给予转染了psBTLA质粒的CHO细胞的培养上清处理后,检测DCs表面B7-1的表达,ELISA检测上清中IL-12的分泌;处理后的DCs刺激脾细胞,检测淋巴细胞增殖和细胞因子分泌;检测psBTLA体内转染对宫颈癌细胞系TC-1成瘤小鼠DCs表达B7-1和肿瘤生长的影响.结果 成功构建小鼠BTLA胞外段的真核表达载体psBTLA,获得了稳定转染psBTLA的CHO细胞,在其培养上清检测到BTLA胞外段(sBTLA)的表达.DCs经抗原肽刺激后BTLA、HVEM表达均上调,加入含sBTLA的上清处理后上调B7-1,上清中分泌的IL-12增加,与脾细胞共培养时促进细胞增殖和IL-2、IFN-γ的分泌;体内基因转染psBTLA促进DCs表达B7-1以及抑制肿瘤生长.结论 通过sBTLA阻断BTLA-HVEM共抑制通路,可以进一步促进DCs的功能,更好地激活淋巴细胞,促进抗肿瘤免疫应答.     

人脐血源性MSCs成骨诱导分化后对DCs的免疫抑制研究

目的探讨人脐血源性间充质干细胞(mesenchymal stem cells derived from umbilical cord blood,UCB-MSCs)经成骨诱导分化后,对树突状细胞(dendritic cells,DCs)的分化、成熟及免疫功能的影响。方法对UCB-MSCs通过细胞形态、表面标记及成骨诱导分化能力进行鉴定;在外周血单核细胞培养体系中加入GM-CSF+IL-4+TNF-α,刺激DCs诱导分化及成熟;收集与成骨诱导分化前后UCB-MSCs共培养的DCs,流式细胞仪检测DCs免疫表型的表达情况;将成熟DCs作为刺激因素,外周血淋巴细胞作为反应细胞,3H-TdR标记β液体闪烁计数仪检测与成骨诱导分化前后UCB-MSCs共培养后,DCs刺激淋巴细胞增殖能力的变化。结果人UCB-MSCs成骨诱导分化后能抑制DCs表面CD40、CD80、CD83、CD86和MHC-II的表达,上调CD14的表达;DCs具有明显刺激淋巴细胞增殖的功能,而UCB-MSCs成骨诱导分化后能显著抑制DCs刺激的淋巴细胞增殖。结论成骨诱导分化的UCB-MSCs在体外可抑制同种异体DCs的分化、成熟及免疫功能,为UCB-MSCs作为同种异体源性种子细胞在骨组织工程中的应用提供了依据。     

IL-27 renders DC immunosuppressive by induction of B7-H1

IL-27, an IL-12 family member, was initially described as a proinflammatory cytokine. Nevertheless, it also poses anti-inflammatory activity, being involved in suppressing development of TH-17 cells as well as in the induction of inhibitory Tr1 cells. Recent data obtained in mice suggest that it can down-modulate the function of APCs. However, until now, nothing was known about the influence of IL-27 on human DCs. We investigated the effect of IL-27 on in vitro human MoDCs and on ex vivo blood DCs. Our results show that treatment of mDCs with IL-27 led to specific up-regulation of surface expression of several molecules, including B7-H1, in the absence of general DC maturation. Moreover, we demonstrated that IL-27-treated DCs exhibit a reduced capacity to stimulate proliferation and cytokine production of allogeneic T cells as compared with control DCs. Decisively, we identified B7-H1 as a crucial molecule, responsible for suppressive effects of "IL-27 DC" on T cells. Our data demonstrate for the first time that in addition to the dual role of IL-27 in the modulation of T cell activation and differentiation, human IL-27 modulates an immune response through DCs, i.e., by inducing immunosuppressive B7-H1 molecules and reducing the stimulatory potential of DCs.     

Expression of programmed-death receptor ligands 1 and 2 may contribute to the poor stimulatory potential of murine immature dendritic cells

Recent data have revealed that Ag presentation by immature dendritic cells (imDCs) plays a role in establishing and maintaining T-cell tolerance, but the mechanism remains unclear. PD-L1 and PD-L2, ligands for programmed-death receptor 1 (PD-1), members of the expanding B7 family, were highlighted for their inhibitory role in T-cell responses. Here, we show that blockade of PD-1 ligands on imDCs resulted in enhanced T-cell proliferation, which is perhaps due to the enhancement of IL-2 production from DC-stimulated T cells. PD-1 ligands blockade on mDCs did not show a significant stimulatory effect as markedly as imDCs. The inhibitory effects of PD-1 ligands would be dependent on maturation status of DCs, where attenuated positive costimulatory molecules provided the opportunity for PD-1 ligands to exert their strong capacity. Our data are consistent with the hypothesis that imDCs have an inhibitory bias, and indicate that PD-L1 and PD-L2 contribute to the poor stimulatory capacity of imDCs.     

Enhanced in vitro stimulation of rhesus macaque dendritic cells for activation of SIV-specific T cell responses

The macaque-simian immunodeficiency virus (SIV) system is one of the best animal models available to study the role of dendritic cells (DCs) in transmission and pathogenesis of HIV, as well as to test DC-based vaccine and therapeutic strategies. To better define and optimize this system, the responsiveness of macaque monocyte-derived DCs to a variety of maturation stimuli was examined. Characteristic immunophenotypic and functional DC maturation induced by standard monocyte conditioned medium (MCM) was compared to the activation induced by a panel of stimuli including soluble CD40L, LPS, Poly I:C, PGE₂/TNF, and a cocktail mixture of PGE₂/TNF/IL-1β/IL-6. Immunophenotypic analysis confirmed that all stimuli induced stable up-regulation of CD25, CD40, CD80, CD83, CD86, HLA-DR, DC-LAMP (CD208), and DEC-205 (CD205). In general, macaque DCs exhibited weaker responses to LPS and Poly I:C than human DCs, and soluble CD40L stimulation induced variable expression of CD25. Interestingly, while the endocytic capacity of CD40L-matured cells was down-modulated comparably to DCs matured with MCM or the cocktail, the T cell stimulatory activity was not enhanced to the same extent. The particularly reproducible and potent T cell stimulatory capacity of cocktail-treated DCs correlated with a more homogenous mature DC phenotype, consistently high levels of IL-12 production, and better viability upon reculture compared to DCs activated by other stimuli. Furthermore, cocktail-matured DCs efficiently captured and presented inactivated SIV to SIV-primed T cells in vitro. Thus, the cocktail represents a particularly potent and useful stimulus for the generation of efficacious immunostimulatory macaque DCs.     

B7-H1 up-regulation impairs myeloid DC and correlates with disease progression in chronic HIV-1 infection

Impaired myeloid dendritic cells (mDC) fail to elicit host antiviral immune responses, leading to disease progression in HIV-1 infection. However, mechanisms underlying mDC suppression remain elusive. In this study, we found that the T-cell co-stimulatory molecule programmed death-1 ligand-1 (B7-H1) is significantly up-regulated on peripheral mDC in HIV-1-infected typical progressors and AIDS patients, but is maintained at a relatively low level in long-term non-progressors. Successful immune reconstitution after highly active antiretroviral therapy, indicated by full suppression of HIV-1 replication and substantial increases of CD4 T-cell counts, correlated with a decrease in B7-H1 expression. Importantly, we also found that X4 HIV-1 isolates directly induced B7-H1 expression on mDC in vitro, while adding antiviral agents hampered this B7-H1 up-regulation. Blockade of B7-H1 in vitro strongly enhanced mDC-mediated allostimulatory capacity and IL-12 production. In contrast, B7-H1 ligation with soluble programmed death-1 (PD-1) reduced mDC maturation and IL-12 production but increased mDC apoptosis and IL-10 production. Thus, B7-H1 up-regulation may inhibit mDC-mediated immune response, thereby facilitating viral persistence and disease progression in HIV-1-infected patients. This study provides new evidence that B7-H1 inhibitory signaling may reversely mediate functional impairment of mDC in HIV-1 infection, which further supports the notion that B7-H1 blockade represents a novel therapeutic approach to this disease.     

B7-H3单抗交联作用对Mo-DC体外生物学功能的影响

探讨B7-H3分子对人外周血单核细胞来源树突状细胞(Mo-DC)体外成熟和生物学功能的影响。采用常规方法从健康人外周血单核细胞诱导DC,在诱导过程中,加入B7-H3单抗21D4共培养,经流式细胞术检测Mo-DC上B7-H3分子和其他共刺激分子的表达,ELISA试剂盒检测培养上清中细胞因子IL-10和IFN-γ的分泌量,并采用3H-TdR掺入法测定T细胞的增殖。结果:B7-H3分子在未成熟和成熟Mo-DC上均有高水平表达,抗人B7-H3单抗21D4能上调Mo-DC表面CD80、CD86和CD83的表达,提高Mo-DC的共刺激能力,促进T细胞的体外增殖,并能显著促进T细胞分泌IL-10。由此表明,B7-H3单抗21D4交联作用可以促进Mo-DC体外成熟,上调其共刺激T细胞的能力。     

B7-H3： Another Molecule Marker for Mo-DCs？

Using a newly generated monoclonal antibody （2E6） against human B7-H3, we explored the expression of the molecule on dendritic cells derived from monocytes （Mo-DCs）. Its expression was examined by means of immunostaining and flow cytometric （FCM） analysis. The results showed that B7-H3 was expressed in the course of Mo-DC maturation induced with interleukin 4 （IL-4） and granulocyte/macrophage colony-stimulating factor （GM-CSF）. The expression could be detected at all the stages of Mo-DC differentiation, and remained at a quite stable level. Interestingly, B7-H3 was not expressed by T cells and B cells, even these cells were activated respectively by PHA or PWM. A weak expression could be detected on resting monocytes. These data showed that constitutive expression of B7-H3 at a high level was found on imDCs and mDCs derived from monocytes. Due to no expression on T cells and B cells, we speculate that B7-H3 might be another valuable molecule marker for Mo-DCs.     

Bacillus anthracis lethal toxin attenuates lipoteichoic acid-induced maturation and activation of dendritic cells through a unique mechanism

Lethal toxin (LT), produced by the gram-positive bacterium Bacillus anthracis, was identified as a major etiologic agent causing anthrax due to its strong immunotoxicity. Gram-positive bacteria express lipoteichoic acid (LTA), which is considered as a counterpart to lipopolysaccharide (LPS) of gram-negative bacteria, but differs from LPS in the structure and function. Since dendritic cells (DCs) are essential for the appropriate initiation of immune response, we investigated the effect of LT on LTA-induced DC maturation using immature DCs prepared by differentiation of C57BL/6 mouse bone marrow cells. When immature DCs were matured with LTA in the presence of LT, the expression of representative markers for DC maturation such as CD80, CD83, and CD86 together with MHC class I and II molecules was inhibited. LT ameliorated the attenuation of endocytic capacity during DC maturation by LTA while such effect was not observed in LPS-matured DCs. Furthermore, exposure to LT resulted in a decrease in the expression of pro-inflammatory cytokines including IL-6, TNF-α, and IL-12p40 in LTA-stimulated DCs as in LPS-stimulated DCs. Interestingly, LT showed a minimal change in LTA-induced IL-1β expression while LT highly enhanced the LPS-induced IL-1β expression. Those inhibitory effects might be associated with LT interference of LTA-signaling pathways mediated through mitogen-activated protein kinases (MAPKs) since LT suppressed phosphorylation of MAPK, which was induced by LTA. Meanwhile, no change was observed in the expression of putative anthrax toxin receptors, TEM8 and CMG2, or Toll-like receptor 2. These results suggest that LT suppresses the maturation and activation of DCs stimulated with LTA, similar to the suppression in the LPS-stimulated DCs, but via a distinct mechanism.