IL-2基因修饰对巨噬细胞表型和抗原提呈功能的影响

目的：观察了白细胞介素２（ＩＬ－２）基因修饰的巨噬细胞ＩＬ－２动态分泌水平及对其表面分子的表达和抗原提呈能力变化的影响。方法：通过重组腺病毒介导,将ＩＬ－２基因转染至腹腔巨噬细胞,ＭＭＴ法检测其ＩＬ－２动态和分泌水平,ＦＡＣＳ检测巨噬细胞表型,混合淋巴细胞反应法（ＭＬＲ）测定巨噬细胞抗原提呈能力。结果：ＩＬ－２基因修饰４ｈ后巨噬细胞即可表达较高水平的ＩＬ－２,１８￣４８ｈ之间的ＩＬ－２分泌处于高峰     

MHC I类抗原多肽致敏IL-2基因修饰的树突状细胞对小鼠 引流淋巴结T细胞亚群的影响及其免疫保护作用

目的探讨MHCI类分子限制性肿瘤抗原多肽Mutl体外冲击白细胞介素2(Interleukin-2,IL-2)基因修饰的树突状细胞(Dendrticcells,DC)对小鼠体内特异性免疫的活化机制。方法用腺病毒作为载体介导小鼠IL-2基因修饰DC,用小鼠Lewis肺癌3LL细胞株MHCI类分子限制性八肽Mutl冲击IL-2基因修饰的DC(DC-IL-2-Mutl)免疫小鼠,用流式细胞术(FACS)分析免疫保护小鼠接受3LL细胞再攻击后引流淋巴结内T细胞亚群的比例变化。结果用Mutl冲击的DC免疫的小鼠抵抗3LL细胞再攻击时,引流淋巴结内CD8     

MHCI类抗原多肽致敏IL—2基因修饰的树突状细胞对小鼠引流淋巴结T细胞亚群

目的：探讨ＭＨＣ Ｉ类分子限制性肿瘤抗原多肽Ｍｕｔｌ体外冲击白细胞介素２（Ｉｎｔｅｒｌｅｕｋｉｎ－２,ＩＬ－２）基因修饰的树突状细胞（Ｄｅｎｄｒｔｉｃ ｃｅｌｌｓ,ＣＤ）对小鼠体内特异性免疫的活化机制。方法：用腺病毒作为载体介导小鼠ＩＬ－２基因修饰ＤＣ,用小鼠Ｌｅｗｉｓ肺癌３ＬＬ细胞株ＭＨＣ Ｉ类分子限制性八肽Ｍｕｔｌ冲击ＩＬ－２基因修饰的ＤＣ（ＤＣ－ＩＬ－２Ｍｕｔｌ）免疫小鼠,用流式细胞术（ＦＡＣＳ）分析免疫保护小鼠接受３ＬＬ细胞再攻击后引流淋巴结内Ｔ细胞亚群的比例变化。结果：用Ｍｕｔｌ冲击的ＤＣ免疫的小鼠抵抗３ＬＬ细胞再攻击时,引流淋巴结内ＣＤ８＾＋Ｔ淋巴细胞比例明显升高,ＤＣ－ＩＬ－２－Ｍｕｔｌ免疫保护的小鼠接受３ＬＬ细胞再攻击后引流淋巴结内ＣＤ８＾＋和ＮＫ细胞的比例都明显升高。结论：研究表明ＭＨＣ Ｉ类     

树突状细胞对外源性抗原的摄取和加工机制

树突状细胞 (dendriticcell,DC)是体内功能最强大的专职性抗原提呈细胞 (antigenpresentingcell,APC) ,因其成熟时胞体伸出许多树突状或伪足样突起而得名 ,与其它APC相比 ,DC能高效地内吞、处理及呈递抗原 ,并能激活幼稚型 (na¨lve)T淋巴细胞 ,启动初级免疫应答 ,故在免疫反应中占有极其特殊的地位[1] 。因此 ,深入了解DC对抗原的摄取、加工和MHC分子的生成及作用对揭示DC的抗原提呈机制有重要意义     

树突状细胞与其它APC抗原提呈功能及其作用机制比较

本文对ＤＣ与其它ＡＰＣ（Ｍψ，Ｂ细胞，在纤维细胞等）在抗原提呈功能及其作用机制，影响因素等方面进行了比较，以进一步明确ＤＣ的独特免疫功能。     

IL-10基因修饰的大鼠树突状细胞表型分析及生物学特性的研究

目的研究IL-10基因修饰后的大鼠树突状细胞(DC)的表型及其生物学特性。方法以含IL-10基因的重组腺病毒载体体外转染大鼠骨髓来源的DC,Western blot测定转染后各组DC中IL-10蛋白的表达,流式细胞仪检测各组DC表面抗原CD83、CD86分子的表达情况,混合淋巴细胞反应法测定各组DC刺激同种异体T细胞增殖的能力。结果 IL-10基因修饰组DC可检测到IL-10高表达,表面抗原CD83、CD86低表达,其刺激T淋巴细胞增殖水平较其他各组低。结论 IL-10基因修饰的DC可有效的表达有功能的IL-10,为研究IL-10修饰的DC诱导同种异体移植免疫耐受奠定了基础。     

树突状细胞异质性研究进展

树突状细胞(DC)是一种重要的特异性抗原递呈细胞(APC),在免疫应答的诱导和调节中起重要作用.器官移植后,异质性供体DC与受体组织发生接触,这些细胞连同宿主DC有潜在的激活同种异体反应性T细胞或使之产生耐受的倾向.在鼠及人类中,DC谱系、表型、成热及功能异常复杂,阐明其功能,有助于了解调节耐受/免疫平衡的机制.     

F-actin 重构对树突状细胞形态和功能影响的研究进展

树突状细胞(Dendritic cells,DCs)是目前发现的最有效的抗原提呈细胞,在启动和放大先天性及适应性免疫应答中发挥重要的作用。在其整个生命过程中,它的细胞形态、迁移与黏附、抗原捕获及抗原提呈等多方面与细胞骨架的动态重构存在密切的关系。细胞骨架的动态重构是一个由多种细胞骨架蛋白共同参与调节的复杂的结构体系,随着研究的不断深入,人们对这种结构体系的认知越来越清晰。基于这些研究,本文综述了纤维状肌动蛋白(Filamentous actin, F-actin)重构对树突状细胞形态和功能的影响。     

树突状细胞与趋化因子的研究进展

树突状细胞(dendritic cell,DC)是功能最强的抗原提呈细胞,广泛存在于多种器官和组织中。DC前体来源于骨髓CD34^ 细胞,随血液循环分布到抗原可能入侵的部位。这些不成熟DC能持续而有效地吞噬抗原,高表达MHC Ⅰ类、Ⅱ类分子以及协同刺激分子,随后进入脾脏或淋巴结并成熟。成熟DC吞噬作用下降,协     

巨细胞病毒抑制树突状细胞抗原递呈功能

目的： 探讨巨细胞病毒（CMV）对单核细胞来源的树突状细胞（DC）的感染效率及对受染细胞的功能影响。方法: 以50半数细胞培养感染量（TCID50）滴度的CMV与未成熟及成熟DC（imDC，mDC）共培养，逆转录－聚合酶链反应（RT-PCR）方法检测细胞内CMV即刻早期抗原（IEA）mRNA水平，间接免疫荧光技术检测受染细胞内早期抗原（EA）阳性率，流式细胞仪检测细胞胞内病毒晚期抗原pp65表达，BrdU ELISA法检测受染DCs（cmv-imDC,cmv-mDC）刺激异基因T细胞增殖能力。结果: 感染 12 h，cmv-mDC内IEA mRNA水平低于cmv-imDC，相对表达量分别为0.102±0.020和0.862±0.124（P<0.05）。24 h，imDC组EA阳性率高于mDC组，分别为(62.32±14.20)%和(10.78±3.04)%（P<0.01）。72 h，cmv-DC胞内低表达pp65抗原，imDC和mDC中阳性率分别为4.86%和0.82%。与未处理mDC相比，cmv-imDC经成熟诱导因子LPS作用后，其刺激异基因T细胞增殖能力较弱（均P<0.05）；而cmv-mDC，仅当DC/T细胞为 1∶1 时，刺激能力下降（P<0.05）。结论: CMV可有效感染imDC，并在细胞内复制活化；cmv-DC的抗原递呈能力下降。     

Split activity of interleukin-10 on antigen capture and antigen presentation by human dendritic cells: Definition of a maturative step

Human CD1⁺ CD14^- dendritic cells (DC) can be derived from CD14⁺ monocytes using granulocyte/monocyte colony-stimulating factor and interleukin (IL)-4. We have previously shown that IL-10 pre-treatment of such DC significantly inhibited their antigen-presenting capacity to CD4⁺ T cell clones. In this study, we further analyze how IL-10 influences antigen presentation. We first investigated whether IL-10 could alter the early stage of antigen presentation, the capture of antigen. This can be mediated by mannose receptor (MR)-mediated endocytosis and by fluid-phase uptake through macropinocytosis. IL-10-treated DC showed an enhancement of both mechanisms of antigen capture, as indicated by the increase of fluorescein isothiocyanate-dextran uptake through MR and lucifer yellow uptake. However, IL-10-treated DC, irradiated or glutaraldehyde-fixed, were less efficient than untreated DC in stimulating mixed leukocyte reaction as well as in inducing the activation of peptide-specific T cell clones, indicating that IL-10 achieves its effects mainly by modifying the cell surface phenotype of DC. HLA class I and II, as well as intercellular adhesion molecule (ICAM)-1, lymphocyte function-associated antigen-3, B7-1, B7-2 and ICAM-3 expression were either significantly increased or essentially unchanged, and the ability to bind the epitope recognized by the T cell clones was also unaffected regardless of IL-10 treatment. Our study also indicates that as-yet unidentified accessory molecules may play an essential role in T cell activation. Thus, the IL-10-treated DC possess an increased capacity to capture antigen, with a concomitant decreased stimulatory activity. Our study suggests that IL-10-treated DC have the characteristics of highly immature DC (high capture ability, low stimulatory potency) and may represent an early maturative step of human DC of monocytic origin.     

IL-18基因修饰增强肿瘤抗原多肽致敏的树突状细胞体内诱导的抗肿瘤免疫反应

目的 :研究肿瘤抗原多肽致敏的白细胞介素 18(IL 18)基因修饰的树突状细胞体内诱导的抗肿瘤免疫反应。方法 :①以Lewis 3LL肺癌细胞特异性抗原肽mut1冲击致敏IL 18基因修饰的骨髓来源的树突状细胞 (DC IL 18 mut1) ,每次用其 1× 10 5 只皮下免疫小鼠 2次 ,然后测定脾细胞的NK活性及CTL杀伤活性 ;②以DC IL 18 mut1每次 2× 10 5 只皮下免疫 1次 ,然后再以 5× 10 53LL细胞攻击 ,在诱导及效应阶段分别以单抗阻断不同免疫成份 ,观察肿瘤的生长。结果 :以DC IL 18 mut1皮下免疫后可诱导出比DC mut1等免疫组更高水平的 3LL肺癌细胞特异性CTL ,并使NK活性明显增加 ;单抗体内阻断实验提示在DC IL 18 mut1免疫诱导阶段 ,CD4 + T细胞和抗原共刺激分子、IFN γ均起到重要作用 ,而效应阶段CD8+ T、IFN γ、NK起作用 ,而CD4 + T则是非必需的。结论 :DC IL 18 mut1皮下免疫后可诱导高水平的抗肿瘤免疫活性 ,其机理与抗原有效提呈、特异性CTL诱导、NK活性增加以及CD4 + 、CD8+ T、NK细胞、IFN γ参与密切相关。     

Characteristics of antigen-independent and antigen-dependent interaction of dendritic cells with CD4+ T cells

Dendritic cells (DC) are the main antigen-presenting cells for the initiation of primary T cell-mediated immune responses. In the first stage of activation, T cells bind to DC in an antigen-independent manner. We studied the adhesion characteristics of human CD4⁺ T cells to DC generated from CD34⁺ hematopoietic progenitors following 12 to 13 days of culture in the presence of granulo-cyte/macrophage colony-stimulating factor and tumor necrosis factor-α. A majority of these cells had the morphology, phenotype and functions of DC. CD4⁺ T/DC adhesion was measured by means of fluorescence microscopy and flow cytometry. Four independent receptor/ligand pathways, LFA-1/ICAM, ICAM/LFA-1, CD2/LFA-3 and CD28/CD80, were involved in the transient adhesion of DC to CD4⁺ T cells in antigen-independent and specific alloantigen-dependent situations, as shown by blocking experiments using monoclonal antibodies. The antibodies also blocked a primary mixed lymphocyte reaction (MLR) in which DC were used as stimulatory cells. Adhesion of alloreactive CD4⁺ T cells to antigen-presenting DC was stronger than that of resting CD4⁺ T cells, while peak adhesion occurred after 5 and 20 min, respectively. The LFA-1 ligands involved in adhesion of resting CD4 T cells to DC and alloreactive CD4⁺ T cells to specific DC differed in part, since ICAM-3 on resting T cells and ICAM-1 on alloreactive T lymphocytes preferentially bound LFA-1. Studies of interactions between DC and phorbol ester-activated T cells expressing the CD40 ligand revealed a fifth independent adhesion pathway, CD40/CD40 ligand. CD4-mediated regulation of CD4⁺ T/DC adhesion was suggested by the observation that preincubation of CD4⁺ T cells and DC individually with anti-CD4 antibodies inhibited adhesion. In addition, antibodies specific for HLA class II molecules inhibited adhesion when used to pretreat DC but not alloactivated CD4⁺ T cells.     

Glucocorticoids down-regulate dendritic cell function in vitro and in vivo

Exogenous glucocorticoid hormones are widely used as therapeutical agents, whereas endogenous glucocorticoids may act as physiological immunosuppressants involved in the control of immune and inflammatory responses. The optimal activation of T lymphocytes requires two distinct signals: the major histocompatibility complex-restricted presentation of the antigen and an additional co-stimulatory signal provided by the antigen-presenting cells. There is ample evidence that, among the cells able to present the antigen, the dendritic cells (DC) have the unique property to activate antigen-specific, naive T cells in vitro and in vivo, and are therefore required for the induction of primary immune responses. In this work, we tested whether glucocorticoids affected the capacity of DC to sensitize naive T cells. Our data show that, in vitro, the steroid hormone analog dexamethasone (Dex) affects the viability of DC, selectively downregulates the expression of co-stimulatory molecules on viable DC, and strongly reduces their immunostimulatory properties. In vivo, a single injection of Dex results in impaired antigen presenting function, a finding which correlates with reduced numbers of splenic DC. These results show that glucocorticoids regulate DC maturation and immune function in vitro and in vivo and suggest that this mechanism may play a role in preventing overstimulation of the immune system.     

Th1 cells induce and Th2 inhibit antigen-dependent IL-12 secretion by dendritic cells

Dendritic cells are the most relevant antigen-presenting cells (APC) for presentation of antigens administered in adjuvant to CD4⁺ T cells. Upon interaction with antigen-specific T cells, dendritic cells (DC) expressing appropriate peptide-MHC class II complexes secrete IL-12, a cytokine that drives Th1 cell development. To analyze the T cell-mediated regulation of IL-12 secretion by DC, we have examined their capacity to secrete IL-12 in response to stimulation by antigen-specific Th1 and Th2 DO11.10 TCR-transgenic cells. These cells do not differ either in TCR clonotype or CD40 ligand (CD40L) expression. Interaction with antigen-specific Th1, but not Th2 cells, induces IL-12 p40 and p75 secretion by DC. The induction of IL-12 production by Th1 cells does not depend on their IFN-γ secretion, but requires direct cell-cell contact mediated by peptide/MHC class II-TCR and CD40-CD40L interactions. Th2 cells not only fail to induce IL-12 secretion, but they inhibit its induction by Th1 cells. Unlike stimulation by Th1, inhibition of IL-12 production by Th2 cells is mediated by soluble molecules, as demonstrated by transwell cultures. Among Th2-derived cytokines, IL-10, but not IL-4 inhibit Th1-driven IL-12 secretion. IL-10 produced by Th2 cells appears to be solely responsible for the inhibition of Th1-induced IL-12 secretion, but it does not account for the failure of Th2 cells to induce IL-12 production by DC. Collectively, these results demonstrate that Th1 cells up-regulate IL-12 production by DC via IFN-γ-independent cognate interaction, whereas this is inhibited by Th2-derived IL-10. The inhibition of Th1-induced IL-12 production by Th2 cells with the same antigen specificity represents a novel mechanism driving the polarization of CD4⁺ T cell responses.     

Targeting dendritic cells to advance cross-presentation and vaccination outcomes

Dendritic cells (DCs) are a complex network of specialised antigen-presenting cells that are critical initiators of adaptive immunity. Targeting antigen directly to DCs in situ is a vaccination strategy that selectively delivers antigen to receptors expressed by DC subtypes. This approach exploits specific DC subset functions of antigen uptake and presentation. Here, we review DC-targeted vaccination strategies that are designed to elicit effective cross-presentation for CD8⁺ T cell immunity. In particular, we focus on approaches that exploit receptors highly expressed by mouse and human cDCs equipped with superior cross-presentation capacity. These receptors include DEC205, Clec9A and XCR1. Targeting DC receptors Clec12A, Clec4A4 and mannose receptor is also reviewed. Outcomes of DC-targeted vaccination in mouse models through to human clinical trials is discussed. This is a promising new vaccination approach capable of directly targeting the cross-presentation pathway for prevention and treatment of tumours and infectious diseases.     

Induction of immunosuppressive functions of dendritic cells in vivo by CD4+CD25+ regulatory T cells: role of B7-H3 expression and antigen presentation

Suppressive functions of CD4+CD25+ regulatory T cells (Treg) are mainly studied by their interaction with conventional T cells. However, there is evidence that Treg also interact with antigen-presenting cells (APC), leading to suppression of APC function in in vitro coculture systems. Studying the in vivo distribution of Treg after injection, we found that Treg are located in direct proximity to dendritic cells (DC) and affect their functional maturation status. After contact to Treg, DC up-regulate the inhibitory B7-H3 molecule and display reduced numbers of MHC-peptide complexes, leading to impaired T cell stimulatory function. When Treg-exposed DC were used to immunize animals against antigens, the DC failed to produce a robust immune response as compared to control DC. Thus, these data indicate that Treg are able to inhibit DC activation and produce an inhibitory phenotype of DC. Accordingly, Treg may recruit DC for the amplification of immunosuppression by restraining their maturation in vivo and inducing an immunosuppressive phenotype of DC.     

The role of dendritic cells in cancer and anti-tumor immunity

Dendritic cells (DC) are key sentinels of the host immune response with an important role in linking innate and adaptive immunity and maintaining tolerance. There is increasing recognition that DC are critical determinants of initiating and sustaining effective T-cell-mediated anti-tumor immune responses. Recent progress in immuno-oncology has led to the evolving insight that the presence and function of DC within the tumor microenvironment (TME) may dictate efficacy of cancer immunotherapies as well as conventional cancer therapies, including immune checkpoint blockade, radiotherapy and chemotherapy. As such, improved understanding of dendritic cell immunobiology specifically focusing on their role in T-cell priming, migration into tissues and TME, and the coordinated in vivo responses of functionally specialized DC subsets will facilitate a better mechanistic understanding of how tumor-immune surveillance can be leveraged to improve patient outcomes and to develop novel DC-targeted therapeutic approaches.