CD4+效应T细胞的新成员——Th17细胞

在抗原的刺激下，初始CD4^＋T细胞被诱导分化为效应或调节T细胞，传统上CD4^＋效应T细胞因产生的细胞因子的不同被分为两个亚群：Th1细胞——主要促进细胞内感染的病原体的清除，由IL-12诱导分化，产生的主要细胞因子是IFN-γ；和Th2细胞——主要促进寄生虫感染的清除（如蠕虫），由IL-4诱导分化，主要产生IL-4、IL-5、IL-13。     

树突状细胞扩增抗原特异性CD4+ CD25+调节性T细胞研究进展

CD4+CD25+调节性T细胞(Tr)是同时具有免疫低反应性和免疫抑制性功能两大特征的T细胞.研究证实,CD4+ CD25+ Tr在抑制器官特异性自身免疫性疾病及GVHD是抗原特异性的,因此,应用器官特异性而不是多克隆性的Tr将大大促进以Tr为基础的免疫治疗.而具有调节活性的CD4+ CD25+ Tr仅占人类外周血CIM+ T细胞的1%～2%,因此,研究体外大量扩增的方法 对于以Tr基础的治疗至关重要.研究表明,树突状细胞(DC)作为机体强有力的专职抗原递呈细胞可以扩增具有抗原特异性的CD4+ CD25+ Tr且能增加后者的抑制活性,这为治疗自身免疫性疾病及GVHD提供了新的治疗前景.     

初始CD4+T和记忆性Th1细胞在淋巴器官的分布和IFN-γ的表达

目的比较观察抗原特异性初始CD4^ T细胞和效应性,记忆性。Th1细胞在体内外IFN-γ的产生和在淋巴组织的分布。方法将标记相同数量的OVA-抗原受体转基因小鼠(OVA-TCR-Tg)的初始CD4^ T细胞和Th1细胞被动输给正常小鼠后,利用流式细胞仪在单个细胞水平上观察初始CD4^ T细胞和Th1细胞在体内淋巴组织器官的分布和IFN-γ的产生。结果体外经抗原刺激后,大于98％的Th1细胞和4．1％的初始CD4^ T细胞表达IFN-γ。当被动输入机体后,初始CD4^ T细胞主要分布于淋巴结,而Th1细胞主要分布于脾脏。当再次受到抗原的刺激后,记忆性Th1细胞能迅速产生IFN-γ。初始CD4^ T细胞与效应,记忆Th1细胞在淋巴结和脾脏不同的分布,可能与CD62L的表达有关。结论本研究在我们以前研究的基础上进一步探讨了CD4^ T细胞和记忆性Th1细胞的差异。此结果为进一步揭示初始CD4^ T细胞与Th1细胞的差异提供了实验和理论依据。     

PGE_2调节CD4~+T细胞分化的研究进展

前列腺素(prostaglandin,PG)是花生四烯酸的小分子衍生物,在内分泌系统、心血管系统、生殖系统和神经系统中发挥多种生物学效应。PGE_2作为PG比较有代表性的一种亚型,是人体内重要的炎症介质,参与调节CD4~+T细胞的分化及相关细胞因子的分泌,从而影响CD4~+T细胞所介导的疾病的发生发展。本文就PGE_2及其对CD4~+T细胞亚群分化的调节作用进行综述。     

CD4+CD25+T细胞:一类新被认识的免疫调节细胞

CD4+CD25+T细胞是最近才被认识的一类免疫调节细胞,在胸腺产生,主要发挥抑制性免疫调节功能,表达IL-10mRNA,细胞表面表达IL-2受体α链(CD25),本身不产生IL-2,但在体内、外增殖需要外源性IL-2,在体外为无能细胞(anergy cell),CD4+CD25+T细胞发挥免疫抑制作用是通过细胞-细胞接触依赖方式而非细胞因子依赖方式,CD4+CD25+T细胞在调控自身免疫性疾病的发生、炎症反应和T细胞稳态中发挥重要作用.本文拟对CD4+CD25+T细胞的生物学特性及其应用研究的最新进展作一综述.     

CD4+CD25+调节性T细胞研究进展

CD4+CD25+调节性T细胞是调节性T细胞的亚群之一,主要来源于胸腺,具有多种独特的特征,包括可识别自身抗原肽、分泌抑制性细胞因子等.其功能是通过抑制自身反应性T细胞的免疫反应、抑制传统T细胞的活化以及促进一些抑制性细胞因子的分泌等,在维持机体内环境的稳定、肿瘤免疫监测、诱导移植耐受以及自身免疫性疾病的发生中发挥重要作用.     

结核胸液中ESAT-6多肽特异性多功能CD4+T细胞数量及功能分析

目的:检测ESAT-6多肽刺激后,结核性胸膜炎患者胸液细胞中CD4+T细胞细胞因子产生及多功能CD4+T细胞频率,了解ESAT-6特异性CD4+T细胞在结核局部细胞免疫应答中的作用.方法:分离结核性胸膜炎患者胸液细胞(PFCs),ESAT-6混合多肽刺激后检测CD4+T细胞细胞因子分泌、细胞亚群、多功能性CD4+T细胞频率及细胞因子平均荧光强度.结果:BCG、ESAT-6混合多肽和ESAT-6组蛋白刺激PFCs后,主要是CD4+T细胞分泌Th1细胞因子(IFN-γ、IL-2和TNF-α),而CD8+T细胞几乎不产生细胞因子.进一步分析ESAT-6混合多肽刺激PFCs后Th1细胞的亚群组成,依据细胞因子分泌的类型及数量,该特异性Th1细胞可以分为7个不同亚群,且各亚群所占比例不同,其中多功能性T细胞亚群(同时分泌IFN-γ、IL-2和TNF-α)比例较高.细胞因子荧光强度分析表明,依据细胞因子分泌类型的增加,单个细胞水平上不同Th1亚群中各细胞因子表达的量也逐渐增加,即3+>2+>1+细胞.结论:ESAT-6混合多肽刺激结核性胸膜炎患者胸液细胞后,主要诱导CD4+T细胞分泌细胞因子,且Th1亚群中包含多功能性CD4+T细胞,该细胞在单细胞水平上分泌细胞因子的类型和数量也显著高于其他亚群.可能在结核局部感染中发挥关键保护性作用.     

小鼠脾细胞CD4+CD25+调节性T细胞的表型特征

观察CD4+CD25+T和CD4+CD25-T细胞的表型和细胞因子的表达。自小鼠脾脏制备单个细胞悬液,分离CD4+T细胞、CD4+CD25+和CD4+CD25-T细胞,进行细胞表面标记,激活后进行细胞内细胞因子染色,利用流式细胞仪在单个细胞水平上分析细胞表面分子、转录因子和细胞因子表达之间的关系。结果:在CD4+T细胞中,约有7.8%的细胞同时表达CD25分子。与CD4+CD25-T细胞相比,CD4+CD25+T细胞CD44的表达略有增加,CD45RB的表达明显下降,CTLA-4和Foxp3明显增加。以同时表达CTLA-4和Foxp3的细胞为主,其次为单独表达Foxp3的细胞。细胞因子的研究结果表明,与CD4+CD25-T细胞相比,CD4+CD25+T细胞IL-2、IFN-γ明显减少,而只产生IL-10的细胞略有增加。CD4+CD25+调节性T细胞无论在表型、转录因子的表达以及细胞因子表达方面均于非调节性T细胞不同。     

CD4+CD25+T细胞与移植免疫耐受

调节性T细胞是机体维持自身耐受的重要组成部分.CD4+CD25+T细胞以持续高表达CD25为特征,可通过细胞间直接接触或分泌TGF-β、IL-10来发挥抑制功能.它广泛参与自身免疫耐受、肿瘤免疫、移植免疫.现就其发育、特性、发挥功能的机制以及在移植免疫耐受中的作用和应用前景作一综述.     

CFSE标记抗原特异性CD4+CD25+T细胞在胰岛移植体内归巢的研究

目的:观察抗原特异性CD4 CD25 Treg细胞在小鼠同种异体胰岛移植后体内的分布特点,探讨抗原特异性CD4 CD25 Treg细胞免疫调节可能机制。方法:构建小鼠同种异体胰岛移植模型。CFSE对抗原特异性CD4 CD25 Treg细胞标记,经尾静脉输注。用组织冰冻切片和流式细胞术动态了解CFSE标记的抗原特异性CD4 CD25 Treg细胞在受体内的分布和增殖变化。结果:抗原特异性CD4 CD25 Treg细胞联合胰岛移植组胰岛移植物平均生存期为(34.57±17.15)d,较胰岛移植组生存时间(10.6±1.82)d,差异有统计学意义(P<0.01)。抗原特异性CD4 CD25 Treg细胞在各级淋巴结均有能定居,但是胰腺淋巴结定居的细胞数量明显多于其他淋巴结。结论:抗原特异性Treg细胞抑制STZ诱导的糖尿病小鼠的急性移植排斥反应,细胞抑制功能与细胞在体内淋巴结的归巢有关。     

Instruction of naive CD4+ T cells by polarized CD4+ T cells within dendritic cell clusters

Cooperation between CD4(+) T cells can enhance the response and modulate the cytokine profile, and defining these parameters has become a major issue for multivalent-vaccine strategies.We explored cooperation using adoptive transfer of two populations of TCR transgenic T cells of different specificity. One was transferred without prior activation, whereas the second was activated for five days by antigen stimulation under polarizing culture conditions. Both populations were transferred into a single adoptive host and then primed by particle-mediated DNA delivery. Polarized Th1 cells (inducers) raised the frequency of IFN-gamma(+) cells within a naive (target) population, whereas Th2 inducers raised the frequency of IL-4(+) and reduced that of IL-2(+) cells. These effects were obtained when the genes for both antigens were on the same particle, favoring presentation by the same dendritic cell, but not when on different particles delivered to different dendritic cells. Autonomy of DC clusters allows linked sets of antigens (e.g. from a single pathogen) to maintain cytokine bias, but allows other independent responses, each with their own set of autonomous clusters.     

Age-related increase in the fraction of CD27-CD4+ T cells and IL-4 production as a feature of CD4+ T cell differentiation in vivo.

The influence of ageing on phenotype and function of CD4+ T cells was studied by comparing young (19-28 years of age) and aged (75-84 years of age) donors that were selected using the SENIEUR protocol to exclude underlying disease. An age-related increase was observed in the relative number of memory cells, not only on the basis of a decreased CD45RA and increased CD45RO expression, but also on the basis of a decrease in the fraction of CD27+CD4+ T cells. Our observation that the absolute number of CD45RO+CD4+ T cells was increased, while absolute numbers of CD27-CD4+ T cells remained unchanged in aged donors, indicates that the latter subset does not merely reflect the size of the CD45RO+CD4+ T cell pool. The increased fraction of memory cells in the aged was functionally reflected in an increased IL-4 production and T cell proliferation, when cells were activated with the combination of anti-CD2 and anti-CD28, whereas IL-2 production was comparable between both groups. No differences were observed with respect to proliferative T cell responses or IL-2 production using plate-bound anti-CD3 or phytohaemagglutinin (PHA). The observation that IL-4 production correlated with the fraction of memory cells in young donors but not in aged donors suggests different functional characteristics of this subset in aged donors.     

Differences in responsiveness to CD3 stimulation between naive and memory CD4+ T cells cannot be overcome by CD28 costimulation

Activation of naive CD4⁺ T cells is essential for the induction of primary immune responses. However, this subset is less responsive to signaling via T cell receptor/CD3 (TcR/CD3) complex than memory CD4⁺ cells. For mitogenic activation of T cells, in addition to triggering of the TcR/CD3 complex, costimulatory signals are required that can be generated by surface structures present on the antigen-presenting cells. We investigated here whether differences in responsiveness to TcR/CD3 stimulation of naive and memory cells can be overcome by the costimulatory pathway B7/CD28. Using a B7-dependent system we show that even in the presence of optimal CD28 costimulation, CD4⁺ naive cells still have more stringent TcR/CD3 activation requirements than memory cells. Furthermore, titration of the B7 signal revealed that for activation of naive CD4⁺ cells a higher level of cross-linking of CD28 molecules is required than for memory cells. Thus, our results show that at least two signals are required for activation of both CD4⁺ memory and naive cells, but that for activation of naive cells higher cross-linking of both CD3 and CD28 molecules is necessary.     

卵巢癌细胞培养上清诱导CD4+CD25-T细胞分化为CD4+CD25+调节性T细胞

目的研究卵巢癌细胞培养上清液是否能诱导外周血CD4^＋CD25^- T细胞转变为CD4^＋CD25^＋调节性T细胞。方法将外周血CD4^＋CD25^- T细胞分离后，对照组用CD3和CD28单抗活化，实验组在对照基础上加用卵巢癌细胞株SKOV3培养上清，72h后分离各组的CD25^＋和CD25^-T细胞，溴化脱氧尿嘧啶掺入标记法测定增殖能力及对静息的自体同源CD4^＋CD25^- T细胞的增殖抑制能力，流式细胞仪测定细胞糖皮质激素诱发型TNF受体（glucocorticoid-induced TNFR,GITR）与CTLA-4分子的表达，RT-PCR检测细胞卿mRNA的表达。结果与对照组相反，实验组的CD4^＋CD25^＋T细胞具有免疫抑制功能，自身增殖能力下降，GITR和CTLA-4分子的表达和CD4^＋CD25^＋调节性T细胞相似，并被诱导表达转录因子Foxp3 mRNA。结论卵巢癌细胞分泌的可溶性物质能诱导外周血CD4^＋CD25^-T细胞转化为CD4^＋CD25^＋调节性T细胞。     

Post-thymic in vivo proliferation of naive CD4+ T cells constrains the TCR repertoire in healthy human adults

In spite of thymic involution early in life, the numbers of naive CD4(+) T cells only slowly decline in ageing humans implying peripheral post-thymic naive CD4(+) T cell expansion. This proliferation may compensate for continuous activation and death of naive CD4(+) T cells but may also have negative consequences for protective immunity. Here we show that naive CD4(+) T cells that have proliferated in the periphery are characterized by a highly restricted oligoclonal TCR repertoire. Additionally these cells, which constitute the majority of naive CD4(+) T cells in the elderly, display signatures of recent TCR engagement. Our results demonstrate for the first time that peripheral post-thymic proliferation of naive CD4(+) T cells in healthy human individuals causes a significant contraction of the peripheral TCR repertoire. This age-dependent deterioration of CD4(+) T cell immunity could entail ageing-associated autoimmunity, increased susceptibility to infection or cancer and decreased efficiency of vaccination.     

A monoclonal antibody reactive with a glycophosphatidylinositol-anchored molecule on T cells defines CD4+ T cell subsets

A hybridoma, 25T3 (IgM, χ), was established from MRL/+ mice immunized with an autoreactive T cell line (1/+T1). The antigenicity of the antigen recognized by hybridoma 25T3 (25T3-Ag) expressed on thymic and splenic cells was abolished by treatment with phosphatidylinositol-specific phospholipase C, showing that 25T3-Ag is a glycophosphatdidylinositol-anchored Ag. 25T3-Ag was expressed on approximately 90% of thymocytes. Double-negative, double-positive and CD8 single-positive cells were highly positive for the expression of 25T3-Ag, whereas CD4 single-positive cells were weakly positive (approximately 40 %) or negative (approximately 60%). In the spleen, only CD3⁺ cells (and not B220⁺ nor Mac-1⁺ cells) reacted with 25T3 monoclonal antibody (mAb), indicating that 25T3 mAb is specific for T cells. The majority of splenic CD8⁺ T cells were positive for the expression of 25T3-Ag, although the intensity was weaker than that of thymocytes. In contrast, splenic CD4⁺ T cells were divided into negative (60-70%) and positive (30-40%) populations. Similar staining profiles were observed in BALB/c, C57BL/6, C3H/HeN and AKR/J mice. When BALB/c CD4⁺ T cell subsets were sorted and cultured with irradiated (25 Gy) antigen-presenting cells, stimulation with immobilized anti-CD3 mAb for 2 days resulted in CD4⁺25T3⁺ cells secreting more interleukin-2 and less interleukin-4 than did CD4⁺25T3^? subsets, although the proliferative responses of the cells on day 2 of culture were similar. This suggests that CD4⁺ T cells can be divided into two populations and relatively defined as T helper 1 and T helper 2 cells using this 25T3 mAb. Immunoprecipitation and SDS-PAGE revealed that 25T3-Ag was approximately 70 kDa. These findings are discussed in relation to CD4⁺ T cell subsets.     

CD4+ CD25+调节性T细胞在流产中的研究进展

CD4+CD25+调节性T细胞(Tr)是一个具有独特免疫调节功能的T细胞亚群.Tr免疫学特性主要在于抑制自身反应性T细胞的活化,并参与外周免疫耐受,对维持机体内环境的稳定起重要作用.Tr在流产中发挥重要的免疫调节作用.     

CD4+CD25+调节性T细胞及相关细胞因子的研究进展

胸腺来源的CD4^＋CD25^＋调节性T细胞（Treg）是机体维持自身免疫耐受的重要组成部分，约占CD4^＋T细胞的5％-10％。它具有免疫抑制及免疫无能的特性，是最重要的Treg细胞的亚群之一。近年发现CD4^＋CD25^＋Treg细胞主要通过分泌一些抑制性细胞因子和抑制自身反应性T细胞的免疫应答等方式在维持自身免疫耐受中扮演着重要的角色，其数量的缺乏或功能紊乱会导致各种自身免疫性疾病的发生。     

CD38+ CD45RBlow CD4+ T cells: a population of T cells with immune regulatory activities in vitro

An antibody reactive with CD38 revealed both phenotypic and functional heterogeneity amongst CD45RB^low cells. Functional analysis of the CD38⁺ and CD38⁻ fractions showed that the latter contained T cells which responded to recall antigens and produced high levels of cytokine in response to polyclonal stimulation. In contrast, the CD38⁺ population failed to proliferate or to produce detectable levels of cytokines. Despite appearing unresponsive, the CD38⁺ population significantly inhibited anti-CD3-induced proliferation and cytokine secretion by the reciprocal CD38⁻ population. Immune suppression required stimulation through the TCR and was dependent on a physical interaction between regulatory and responding CD4⁺ populations. It did not involve killing of the responding T cells or secretion of IL-10 or TGF-β. Despite some similarities there is no direct correlation between the in vitro suppression characteristic of the CD38⁺ CD45RB^low subset and in vivo suppression which has been shown to be mediated by unseparated CD45RB^low CD4⁺ T cells. However, these results demonstrate that two functionally distinct subsets of T cells reside within the antigen-exposed or CD45RB^low CD4⁺ T cell population and are thus generated in vivo: (1) conventional memory T cells which proliferate and secrete cytokines in response to activation and (2) a population of regulatory T cells which inhibit T cell activation in vitro. Antibodies reactive with CD38 may provide a useful tool with which to study the role of these T cell subsets in the induction and regulation of the immune response.