类风湿性关节炎中树突状细胞亚群分析

目的 分析类风湿性关节炎患者外周血和关节液中的DC(dendritic cell,DC)亚群以及DC亚群与炎症产生的关系.方法 收集来自西南医院体检中心26例健康人外周血作为对照组,来自西南医院风湿免疫科28例RA患者的外周血及滑膜液作为实验组,其中RA患者的外周血和滑膜液来自同一 RA患者.采用人外周血淋巴细胞分离液...     

浆细胞样树突状细胞研究进展

浆细胞样树突状细胞(pDC)是一类近年来被认识并被证明在免疫应答与免疫耐受中发挥重要作用的免疫细胞，其最突出的功能特点是在病毒、CPG ODN的刺激下产生大量的Ⅰ型干扰素，因此又被称为是天然Ⅰ型干扰素产生细胞(IPC)。由于其在来源、表型等方面都与我们以前所熟知的髓系树突状细胞有着很大的差异并具备独特的功能而引起广泛的关注。本文综述了pDC的来源、表型、功能特点，包括对T细胞的诱导分化及其与疾病的关系等方面的研究进展。     

HIV感染中的浆细胞样树突状细胞研究进展

浆细胞样树突状细胞(pDC)是体内产生干扰素(IFN)-α最有力的细胞,并且是固有免疫和适应性免疫之间的重要联系.HIV-1感染者产生IFN-α不足,循环中pDC数量减少并且功能缺陷,其机制尚不明确.IFN-α在HIV感染中是有益还是有害目前仍存在争论.pDC数量和功能的平衡在HIV发病中起重要作用,利用pDC绝对计数...     

浆细胞样树突状细胞研究进展

浆细胞样树突状细胞(pDC)是一类近年来被认识并被证明在免疫应答与免疫耐受中发挥重要作用的免疫细胞,其最突出的功能特点是在病毒、CPG ODN的刺激下产生大量的Ⅰ型干扰素,因此又被称为是天然Ⅰ型干扰素产生细胞(IPC)。由于其在来源、表型等方面都与我们以前所熟知的髓系树突状细胞有着很大的差异并具备独特的功能而引起广泛的关注。本文综述了pDC的来源、表型、功能特点,包括对T细胞的诱导分化及其与疾病的关系等方面的研究进展。     

树突状细胞亚群的研究进展

树突状细胞 (DC)的主要功能是摄取和处理抗原 ,并向T淋巴细胞递呈抗原。虽然大多数DC具有这一共性 ,但不同类型的DC又具有其不同的功能特性。由DC向T细胞提供的信号既可导致不同的免疫应答 ,也可导致免疫耐受。根据对免疫应答的不同调节效应 ,DC被分为不同的功能亚群。不同的DC亚群可由不同的发育途径而来 ,但它们的发育和功能又被不同的外部因子 ,如微生物产物等而调控。因而对DC功能的研究不应仅限于对正常个体内的DC的研究 ,更重要的是要研究DC系统在外源性微生物入侵后其反应的动态变化。本文对DC亚群及功能研究的最近进展作一简要综述。     

浆细胞样树突状细胞在感染性、免疫性疾病中的研究进展

浆细胞样树突状细胞（PDC）来源于淋巴系造血干／祖细胞,能选择性的诱导免疫应答,并在一定条件下诱导免疫耐受,在抗病毒感染中起重要作用,并可能参与了某些自身免疫性疾病的发生。PDC产生的Ⅰ型IFN（IFN-α／β）在抗病毒过程中很关键,而一定条件下PDC诱导的免疫耐受与调节性T细胞的产生相关。自身免疫性疾病中持续高水平的Ⅰ型IFN提示PDC可能参与此类疾病的发病机制。     

浆细胞样树突状细胞免疫调节功能研究进展

浆细胞样树突状细胞(plasmacytoiddendriticcell,pDC)是近年来颇受关注的一类免疫细胞,其在病毒感染的刺激下可分泌大量的I型干扰素,使其在抗病毒免疫中发挥重要的作用。近年来发现pDC尚具有多种免疫功能,且与其不同的组织来源、诱导激活刺激有关。pDC对T细胞免疫功能具有重要的诱导和调控作用,参与CD4+T细胞失能的形成、CD8+Tr的产生和免疫耐受的诱导。此外,尚可诱导B细胞分化为浆细胞,激活NK细胞,诱导单核细胞向DC分化等。其通过分泌趋化因子可对某些免疫细胞产生趋化效应。本文仅就pDC与T、B、NK、单核细胞等的相互关系的研究进展作一综述,以期对pDC的免疫调节功能有更全面的认识。     

树突状细胞在人巨细胞病毒感染中的作用

人巨细胞病毒(human cytomegalovirus,HCMV)在人群中感染率极高,通过多种免疫逃避机制,实现在宿主体内的长期潜伏感染。树突状细胞(dendritic cells,DC)是重要的抗原提呈细胞,在诱导和维持特异性免疫应答中发挥重要的作用。人体内的DC根据来源、表型分为两群:髓系DC(myeloid DC,mDC)和浆细胞样DC(plasmacytoid DC,pDC),大量研究证实HCMV介导的多种免疫逃避机制中,部分是通过影响DC功能实现的。HCMV不仅可以感染mDC,影响mDC表型、迁移、分泌细胞因子、激活T细胞功能,而且还可以抑制pDC分泌干扰素水平及激活T细胞能力,并且激活过度的B细胞反应,导致机体抗病毒细胞免疫反应的抑制和体液免疫紊乱,实现病毒长期潜伏感染。本文主要讨论HCMV是如何改变两种DC亚型的功能以实现免疫逃避目的。     

浆细胞样树突状细胞与免疫耐受

浆细胞样树突状细胞(PDC)来源于淋巴系干细胞,其表面标志、功能有别于髓系DC,不仅在抗病毒免疫中发挥重要作用,而且通过多种途径诱导T细胞失能和调节性T细胞的形成,从而参与免疫耐受的诱导.PDC诱导T细胞免疫耐受的分子机制与吲哚胺2,3-双加氧酶(IDO)-色氨酸代谢通路和具有抑制功能的膜分子密切相关.深入阐明PDC诱导耐受的机制,将为免疫耐受异常相关的疾病的治疗提供新方案.     

浆细胞样树突状细胞与其他免疫细胞相互关系研究进展

浆细胞样树突状细胞(pDC)是一类近年来被认识并证明在免疫应答与免疫耐受中发挥重要作用的免疫细胞,其功能特点在于活化后大量快速分泌Ⅰ型IFN,并能够通过Ⅰ型干扰素途径增强自然杀伤细胞(NK细胞)、T淋巴细胞、B淋巴细胞以及树突状细胞(DC)的功能,之后分化为一类独特的成熟DC,参与调节T细胞功能,从而有效地连接了固有免疫和适应性免疫.     

Langerhans cells and more: langerin-expressing dendritic cell subsets in the skin

Summary: Langerhans cells (LCs) are antigen-presenting dendritic cells (DCs) that reside in epithelia. The best studied example is the LC of the epidermis. By electron microscopy, their identifying feature is the unique rod- or tennis racket-shaped Birbeck granule. The phenotypic hallmark is their expression of the C-type lectin receptor langerin/CD207. Langerin, however, is also expressed on a recently discovered population of DC in the dermis and other tissues of the body. These ‘dermal langerin⁺ dendritic cells’ are unrelated to LCs. The complex field of langerin-negative dermal DCs is not dealt with here. In this article, we briefly review the history, ontogeny, and homeostasis of LCs. More emphasis is laid on the discussion of functional properties in vivo. Novel models using genetically engineered mice are contributing tremendously to our understanding of the role of LCs in eliciting adaptive immune responses against pathogens or tumors and in inducing and maintaining tolerance against self antigens and innocuous substances in vivo. Also, innate effector functions are increasingly being recognized. Current activities in this area are reviewed, and possibilities for future exploitation of LC in medicine, e.g. for the improvement of vaccines, are contemplated.     

Profiling dendritic cell subsets in the patients with active pulmonary tuberculosis

Dendritic cell (DC) plays an important role in the immune response against pulmonary tuberculosis. However, the phenotypic profile of DC subsets in peripheral blood in individuals with active pulmonary tuberculosis (APT) is still inconclusive. Here, we demonstrated that the absolute numbers of total DC (tDC), myeloid DC (mDC) and plasmacytoid DC (pDC) in individuals with APT were decreased compared to healthy controls (HCs). The decreased number of DCs, especially of pDC, seems to be a useful diagnostic marker of APT. Meanwhile, the number of DCs was associated with the prolonged/complicated TB, ATD treatment effect and lymphocyte immune reactions, as manifested that relapsed APT patients with a higher number of tDC and lower number of pDC compared to newly diagnosed patients. Interestingly, mDC from APT patients displayed high expressions of CD83 and CCR7, but pDC displayed low expressions of CD83 and CCR7. Moreover, DCs from APT patients expressed lower levels of HLA-DR and CD80, but expressed a higher level of CD86 than those from HCs. However, the antigen uptake capacity of DC subsets was not different between APT and HCs, despite the antigen uptake capacity of pDC was much lower than that of mDC in both APT patients and HCs. Our data represent a systematic profile of DC subsets in the blood of APT patients, and would represent a useful biomarker for APT.     

Expression of C-type lectin receptors by subsets of dendritic cells in human skin

C-type lectins are cell surface receptors that recognize carbohydrate structures which are often part of microbial pathogens. Several of these molecules are expressed on dendritic cells and are involved in antigen uptake. Expression of C-type lectins on dendritic cells of the human skin, i.e. Langerhans cells of the epidermis and dermal dendritic cells, has been incompletely studied to date. We therefore investigated C-type lectins in situ and on dendritic cells obtained by migration from skin explants by immunofluorescence and flow cytometry. Emphasis was laid on expression patterns of DEC-205/CD205 and BDCA-2, a marker for plasmacytoid dendritic cells. Langerhans cells in situ expressed low levels of DEC-205. Expression was upregulated upon maturation in skin explant organ culture. Most dermal dendritic cells were found to be positive for DEC-205 and DC-SIGN/CD209. Few BDCA-2-expressing cells were found in most skin samples. They were located in small groups in the dermis close beneath the basement membrane. The vast majority of all types of dendritic cells in normal human skin was of immature phenotype, i.e. did not express DC-LAMP/CD208. It is concluded that normal appearing human skin harbors different subsets of dendritic cells including few scattered BDCA-2-expressing cells, presumably plasmacytoid dendritic cells, expressing variable sets of C-type lectin receptors. This may critically contribute to the capacity of the skin immune system to flexibly respond to the world of microbial pathogens.     

Human dendritic cell subsets display distinct interactions with the pathogenic mould Aspergillus fumigatus

The mould Aspergillus fumigatus is primarily an opportunistic pathogen of immunocompromised patients. Once fungal spores have been inhaled they encounter cells of the innate immune system, which include dendritic cells (DCs). DCs are the key antigen-presenting cells of the immune system and distinct subtypes, which differ in terms of origin, morphology and function.This study has systematically compared the interactions between A. fumigatus and myeloid DCs (mDCs), plasmacytoid DCs (pDCs) and monocyte-derived DCs (moDCs). Analyses were performed by time-lapse video microscopy, scanning electron microscopy, plating assays, flow cytometry, 25-plex ELISA and transwell assays.The three subsets of DCs displayed distinct responses to the fungus with mDCs and moDCs showing the greatest similarities. mDCs and moDCs both produced rough convolutions and occasionally phagocytic cups upon exposure to A. fumigatus whereas pDCs maintained a smooth appearance. Both mDCs and moDCs phagocytosed conidia and germ tubes, while pDCs did not phagocytose any fungi. Analysis of cytokine release and maturation markers revealed specific differences in pro- and anti-inflammatory patterns between the different DC subsets.These distinct characteristics between the DC subsets highlight their differences and suggest specific roles of moDCs, mDCs and pDCs during their interaction with A. fumigatus in vivo.     

Longitudinal alteration of circulating dendritic cell subsets and its correlation with steroid treatment in patients with severe acute respiratory syndrome

In this study, we found that 74 patients with severe acute respiratory syndrome (SARS) exhibited a rapid, dramatic decrease in numbers of circulating myeloid and plasmacytoid dendritic cells (mDCs and pDCs) during the first 2 weeks of illness (5.3- and 28.4-fold reductions for mDCs and pDCs compared with 25 healthy individuals, respectively), with slow return to normal cell numbers during convalescence (weeks 5–7 of illness on average). In addition, numbers of circulating CD4 and CD8 T cells exhibited milder reductions (2.1- and 1.8-fold at week 1) and earlier return to normal at a mean of weeks 3 and 4, respectively. A significant inverse correlation was found between numbers of DC and T-cell subsets and high-dose steroid treatment. Our novel findings thus suggest that the acute SARS-coronavirus infection probably contributes to the initial reduction of DC and T-cell subsets in blood, and that high-dose steroid administration may subsequently exacerbate and prolong low expression of the cell subsets. These findings will aid the framing of further studies of the immunopathogenesis of SARS.     

CpG ODN enhance antigen-specific NKT cell activation via plasmacytoid dendritic cells

Human Valpha24+ Vbeta11+ natural killer T cells (NKT cells) are "natural memory" T cells that detect glycolipid antigens such as alpha-galactosylceramide (alpha-GalCer) presented on CD1d. In the present study we found that highly purified Valpha24+ NKT cells lack TLR9 mRNA, and thus are not sensitive towards stimulation with CpG oligodeoxynucleotides (ODN). Within PBMC, however, CpG ODN synergistically activated NKT cells stimulated with their cognate antigen alpha-GalCer. Depletion of plasmacytoid dendritic cells (PDC) or myeloid dendritic cells (MDC) revealed that both DC subsets were necessary for the synergistic activation of NKT cells by alpha-GalCer and CpG ODN. While PDC were responsible for the stimulation of NKT cells with CpG ODN, MDC but not PDC presented alpha-GalCer via CD1d. Partial activation of NKT cells was mediated by PDC-derived IFN-alpha, whereas full activation of NKT cells as indicated by IFN-gamma production required cell-to-cell contact of PDC and NKT cells in addition to IFN-alpha; OX40 was involved in this interaction. We conclude that CpG-activated PDC enhance alpha-GalCer-specific NKT cell activation, and bias activated NKT cells towards a Th1 phenotype. Our results lead to a novel concept of PDC function: to regulate effector activity of antigen-stimulated T cells in a cell contact-dependent manner without the need of simultaneous presentation of the cognate T cell antigen.     

Human dendritic cell subsets

Dendritic cells are highly adapted to their role of presenting antigen and directing immune responses. Developmental studies indicate that DCs originate independently from monocytes and tissue macrophages. Emerging evidence also suggests that distinct subsets of DCs have intrinsic differences that lead to functional specialisation in the generation of immunity. Comparative studies are now allowing many of these properties to be more fully understood in the context of human immunology.