Regulatory CD4+CD25+ T cells restrict memory CD8+ T cell responses

CD4+ T cell help is important for the generation of CD8+ T cell responses. We used depleting anti-CD4 mAb to analyze the role of CD4+ T cells for memory CD8+ T cell responses after secondary infection of mice with the intracellular bacterium Listeria monocytogenes, or after boost immunization by specific peptide or DNA vaccination. Surprisingly, anti-CD4 mAb treatment during secondary CD8+ T cell responses markedly enlarged the population size of antigen-specific CD8+ T cells. After boost immunization with peptide or DNA, this effect was particularly profound, and antigen-specific CD8+ T cell populations were enlarged at least 10-fold. In terms of cytokine production and cytotoxicity, the enlarged CD8+ T cell population consisted of functional effector T cells. In depletion and transfer experiments, the suppressive function could be ascribed to CD4+CD25+ T cells. Our results demonstrate that CD4+ T cells control the CD8+ T cell response in two directions. Initially, they promote the generation of a CD8+ T cell responses and later they restrain the strength of the CD8+ T cell memory response. Down-modulation of CD8+ T cell responses during infection could prevent harmful consequences after eradication of the pathogen.     

CD4+CD25+ T cells regulate virus-specific primary and memory CD8+ T cell responses

Naturally occurring CD4+CD25+ regulatory T cells appear important to prevent activation of autoreactive T cells. This article demonstrates that the magnitude of a CD8+ T cell-mediated immune response to an acute viral infection is also subject to control by CD4+CD25+ T regulatory cells (Treg). Accordingly, if natural Treg were depleted with specific anti-CD25 antibody before infection with HSV, the resultant CD8+ T cell response to the immunodominant peptide SSIEFARL was significantly enhanced. This was shown by several in vitro measures of CD8+ T cell reactivity and by assays that directly determine CD8+ T cell function, such as proliferation and cytotoxicity in vivo. The enhanced responsiveness in CD25-depleted animals was between three- and fourfold with the effect evident both in the acute and memory phases of the immune response. Surprisingly, HSV infection resulted in enhanced Treg function with such cells able to suppress CD8+ T cell responses to both viral and unrelated antigens. Our results are discussed both in term of how viral infection might temporarily diminish immunity to other infectious agents and their application to vaccines. Thus, controlling suppressor effects at the time of vaccination could result in more effective immunity.     

低剂量西罗莫司协同CD4~+CD25~+ T-reg诱导大鼠肝移植免疫耐受的实验研究

目的我们通过体外诱导、扩增并分选出CD4+CD25+T-reg回输入受体大鼠,并协同低剂量西罗莫司去诱导大鼠肝移植免疫耐受,研究探讨CD4+CD25+T-reg细胞亚群在移植免疫耐受过程中扮演的角色。方法将实验动物分为急性排斥组(DA→LEW)、免疫耐受组(LEW→DA)、低剂量西罗莫司(0.1 mg·kg-1·d-1)和CD4+CD25+T-reg协同作用组(实验组)。每组8只实验动物。各组肝移植大鼠的存活率比较,应用HE染色法观察移植肝术后7 d组织病理学变化,检测CD4+CD25+Foxp3+T-reg细胞亚群在各组大鼠移植肝脏、外周血总单核细胞数中所占的百分比。RT-PCR检测术后7 d移植肝脏Foxp3 m RNA的表达水平。用ELISA检测血浆中细胞因子IL-10、TGF-β的水平。结果实验组对比排斥组,能够长期存活,获得免疫耐受(P<0.05)。实验组移植肝脏中CD4+CD25+Foxp3+T-reg细胞亚群所占的比例明显高于排斥组(P<0.001),且在移植肝脏中,实验组Foxp3 m RNA表达含量明显增加(P<0.001)。实验组血浆中细胞因子IL-10、TGF-β的表达水平高于排斥组(P<0.001)。结论我们通过流式细胞分选技术将体外扩增诱导成熟的受体大鼠CD4+CD25+T-reg细胞分离收集,然后回输受体协同低剂量的西罗莫司能够成功地诱导了长期肝移植免疫耐受。从而为临床应用CD4+CD25+T-reg细胞抑制免疫排斥反应,诱导移植免疫耐受提供了一条新思路和理论实验依据。     

CD4^＋CD25^＋调节性T细胞与自身免疫病

目的:CD4 CD25 调节性T细胞是一群具有免疫调节或免疫抑制功能的细胞。越来越多的实验证明,CD4 CD25 调节性T细胞在维持外周免疫耐受中起重要作用,这种T细胞的数量减少或功能缺失可导致自身免疫性疾病的发生。本文就CD4 CD25 调节性T细胞及其在自身免疫性疾病中作用的研究进展做一综述。资料来源:应用计算机检索CNKI、Medline、EMCC数据库和手工检索2006-2007年的相关文献。检索词为"CD4 CD25 T调节性细胞,自身免疫病,免疫耐受,CD4 CD25 regulatory T cell,Treg,autoimmune disease,immune tolerance"。资料选择:检索范围包括临床研究(不限研究对象的年龄、性别、种族)和基础研究,不限体内和体外研究。资料提炼:共收集到相关文献675篇,选择其中33篇英文文献进行重点阅读和分析。资料综合:CD4 CD25 调节性T细胞具有免疫抑制功能,在机体的免疫调节中发挥重要作用。与其免疫调节功能相关的杀伤性T细胞淋巴细胞相关抗原4、CD45RO、糖皮质激素诱导的肿瘤坏死因子受体、淋巴细胞的无能相关基因等细胞表面分子和白细胞介素2、白细胞介素10、白细胞介素4、转化生长因子β等细胞因子的研究不断深入。此外,CD4 CD25 调节性T细胞功能的发挥还与FOXP3的表达密切相关。CD4 CD25 调节性T细胞数量的减少、抑制功能的受损和(或)细胞表面分子表达的缺陷可能导致1型糖尿病、多发性硬化和炎症性肠病等多种自身免疫病的发生。结论:CD4 CD25 调节性T细胞主要通过细胞接触依赖机制和抑制性细胞因子依赖机制发挥免疫抑制效应。其数量的减少、功能的受损和(或)表面分子表达的缺陷与自身免疫病的发生发展密切相关。     

Direct expansion of functional CD25+ CD4+ regulatory T cells by antigen-processing dendritic cells

An important pathway for immune tolerance is provided by thymic-derived CD25+ CD4+ T cells that suppress other CD25- autoimmune disease-inducing T cells. The antigen-presenting cell (APC) requirements for the control of CD25+ CD4+ suppressor T cells remain to be identified, hampering their study in experimental and clinical situations. CD25+ CD4+ T cells are classically anergic, unable to proliferate in response to mitogenic antibodies to the T cell receptor complex. We now find that CD25+ CD4+ T cells can proliferate in the absence of added cytokines in culture and in vivo when stimulated by antigen-loaded dendritic cells (DCs), especially mature DCs. With high doses of DCs in culture, CD25+ CD4+ and CD25- CD4+ populations initially proliferate to a comparable extent. With current methods, one third of the antigen-reactive T cell receptor transgenic T cells enter into cycle for an average of three divisions in 3 d. The expansion of CD25+ CD4+ T cells stops by day 5, in the absence or presence of exogenous interleukin (IL)-2, whereas CD25- CD4+ T cells continue to grow. CD25+ CD4+ T cell growth requires DC-T cell contact and is partially dependent upon the production of small amounts of IL-2 by the T cells and B7 costimulation by the DCs. After antigen-specific expansion, the CD25+ CD4+ T cells retain their known surface features and actively suppress CD25- CD4+ T cell proliferation to splenic APCs. DCs also can expand CD25+ CD4+ T cells in the absence of specific antigen but in the presence of exogenous IL-2. In vivo, both steady state and mature antigen-processing DCs induce proliferation of adoptively transferred CD25+ CD4+ T cells. The capacity to expand CD25+ CD4+ T cells provides DCs with an additional mechanism to regulate autoimmunity and other immune responses.     

Antigen-dependent proliferation of CD4+ CD25+ regulatory T cells in vivo

The failure of CD25+ regulatory T cells (Tregs) to proliferate after T cell receptor (TCR) stimulation in vitro has lead to their classification as naturally anergic. Here we use Tregs expressing a transgenic TCR to show that despite anergy in vitro, Tregs proliferate in response to immunization in vivo. Tregs also proliferate and accumulate locally in response to transgenically expressed tissue antigen whereas their CD25- counterparts are depleted at such sites. Collectively, these data suggest that the anergic state that characterizes CD25+ Tregs in vitro may not accurately reflect their responsiveness in vivo. These observations support a model in which Treg population dynamics are shaped by the local antigenic environment.     

不同树突状细胞对CD4~+CD25~+Foxp3~+调节性T细胞体外扩增的影响

目的利用不同种类树突状细胞(dendritic cells,DC)体外扩增获得表型和功能稳定的CD4+CD25+Foxp3+调节性T细胞(Treg)。方法免疫磁珠法(MACS)分离Balb/c小鼠CD4+CD25+调节性T细胞,利用与调节性T细胞同基因或异基因成熟DC、未成熟DC和调节性DC刺激其扩增,流式细胞术测定其纯度和表型。以CD4+CD25-T细胞作为反应细胞,验证扩增前后Treg细胞的免疫抑制功能。结果MACS分离的CD4+CD25+调节性T细胞纯度达到(95.38±1.82)%,同基因和异基因DC都能有效刺激Treg细胞体外扩增,其中同基因成熟DC扩增效果最为明显。而且同基因成熟DC扩增后CD4+CD25+调节性T细胞纯度达到(94.16±1.88)%,而且高表达Foxp3分子。当CD4+CD25+调节性T细胞与效应T细胞比例为1∶1时,能够有效的抑制效应T细胞的增殖,而且,同基因成熟DC扩增的CD4+CD25+调节性T细胞的抑制效果比新分离的Treg效果更好。结论同基因成熟DC能够体外扩增表型和功能稳定的Treg细胞。     

供体凋亡淋巴细胞预输注对猪肝移植受体CD4+T、CD8+T、CD4+CD25+调节性T细胞的影响

背景:凋亡细胞能够主动调节机体的免疫功能,并能通过调节机体细胞免疫和体液免疫的途径诱导免疫耐受,但这些结果只在大鼠肝脏移植模型中证实.目的:探讨通过60Co γ射线体外处理后的供体淋巴细胞预输注诱导猪肝移植特异性免疫耐受的作用中,对淋巴细胞亚群的影响.方法:建立非转流小型猪原位肝移植模型.将受体猪随机摸球法均分为2 组:空白对照组,受体猪无特殊处理,行肝移植;淋巴细胞组:受体猪在肝移植前7 d 经耳静脉注射60Co γ射线处理过的5×108 个供体淋巴细胞.观察两组受体猪移植后的存活时间,移植后T 淋巴细胞亚型CD4+T、CD8+T、CD4+CD25+Tr 变化及病理.结果与结论:移植后3 d,两组病理活检均呈急性中、重度排斥反应;移植后6 d,两组均呈急性重度排斥反应.移植后1,3,6 d CD4+T、CD8+T、CD4+CD25+Tr 升降趋势,两组间差异无显著意义(P ＞ 0.05).提示,60Co γ射线体外处理过的淋巴细胞预输注未能够诱导猪同种异体肝移植特异性免疫耐受,未能引起T 淋巴细胞亚群变化有关.     

流式细胞术检测表达FoxP3的CD4+CD25+调节性T细胞

目的 探讨转录因子FoxP3在外周血CD4 CD25 调节性T细胞(Treg)内的表达特性.方法 取正常人外周血单个核细胞(PBMC),经固定/透膜处理进行细胞内染色,用流式细胞术(FCM)检测T细胞内FoxP3.以抗人CD3/CD28诱导T细胞活化,再用定量PCR及FCM术分别检测FoxP3 mRNA及蛋白质表达水平.结果 FoxP3主要表达于CD4 T细胞,尤其是CD25高表达的CD4 T细胞,达97%左右;中等程度表达CD25的细胞中也含有少量FoxP3阳性细胞.T细胞活化后,表达FoxP3的CD4 CD25 T细胞比例显著增高,FCM检测结果与定量PCR结果一致.结论 FoxP3不仅参与维持Treg细胞的功能,也与T细胞的活化有关.FCM检测细胞核内表达的FoxP3分子为研究Treg细胞提供了一种快速、简便的方法.     

同种异基因抗原特异性调节性T细胞的体外扩增

目的建立用人B淋巴细胞体外获得大量的同种异基因抗原特异性调节性T(Treg)细胞的方法,以此检测扩增细胞的表型及其免疫无能性和免疫抑制性。方法第1轮扩增将免疫磁珠分选的人CD4+CD25+T细胞和人B淋巴细胞按1∶4体外混合培养,并加入外源白介素-2(IL-2)和抗-CD28;将第1轮扩增得到的Treg细胞用抗-CD3/CD28包被的免疫磁珠和IL-2刺激,做第2轮扩增以获得更多数量的抗原特异性Treg细胞,分为添加和或未添加免疫抑制剂雷帕霉素(RAPA)2组(n=3)。结果经过2轮的扩增后,在第2轮扩增中未添加RAPA组扩增1×103倍,纯度80%;添加RAPA组扩增0.8×103倍,纯度90%。添加RAPA组得到的Treg细胞的Foxp3、CT-LA4、CD39表达水平高于未添加RAPA组,但是HLA-DR变化不大;未添加RAPA组扩增得到的Treg细胞分泌低水平的IL-2、IL-17、IL-4和IFN-γ,而添加RAPA组得到的Treg细胞几乎不分泌上述各种细胞因子,前者表现出部分免疫反应无能性,后者表现出完全的免疫反应无能性,两者都表现出免疫抑制性功能特征。人B淋巴细胞扩增得到的抗原特异性Treg细胞能够极大地抑制同源抗原引起的免疫反应,而对多克隆刺激的免疫反应抑制能力较弱。结论用人B细胞体外扩增抗原特异性Treg细胞,再通过抗-CD3/CD28包被的免疫磁珠进一步刺激可以体外获得大量的抗原特异性的Treg细胞,加入RAPA后可有效地提高Treg细胞的纯度和免疫抑制力且呈现抗原特异性。     

Spontaneous tumor rejection by cbl-b-deficient CD8+ T cells

The concept of tumor surveillance implies that specific and nonspecific components of the immune system eliminate tumors in the early phase of malignancy. Understanding the biochemical mechanisms of tumor immunosurveillance is of paramount significance because it might allow one to specifically modulate spontaneous antitumor activity. We report that inactivation of the E3 ligase Casitas B cell lymphoma-b (Cbl-b) confers spontaneous in vivo rejection of tumor cells that express human papilloma virus antigens. Moreover, cbl-b(-/-) mice develop significantly fewer ultraviolet B (UVB)-induced skin malignancies and reject UVB-induced skin tumors. CD8(+) T cells were identified as key players in the spontaneous tumor rejection response. Loss of Cbl-b not only enhances antitumor reactivity of CD8(+) T cells but also occurs in the absence of CD4(+) T cells. Mechanistically, cbl-b(-/-) CD8(+) T cells are resistant to T regulatory cell-mediated suppression and exhibit enhanced activation and rapid tumor infiltration. Importantly, therapeutic transfer of naive cbl-b(-/-) CD8(+) T cells is sufficient to mediate rejection of established tumors. Even up to 1 yr after the first encounter with the tumor cells, cbl-b(-/-) mice carry an "anticancer memory." These data identify Cbl-b as a key signaling molecule that controls spontaneous antitumor activity of cytotoxic T cells in different cancer models. Inhibition of Cbl-b is a novel approach to stimulate long-lasting immunity against cancer.     

Human CD4+ CD25hi Foxp3+ regulatory T cells are derived by rapid turnover of memory populations in vivo

While memory T cells are maintained by continuous turnover, it is not clear how human regulatory CD4+ CD45RO+ CD25hi Foxp3+ T lymphocyte populations persist throughout life. We therefore used deuterium labeling of cycling cells in vivo to determine whether these cells could be replenished by proliferation. We found that CD4+ CD45RO+ Foxp3+ CD25hi T lymphocytes were highly proliferative, with a doubling time of 8 days, compared with memory CD4+ CD45RO+ Foxp3- CD25- (24 days) or naive CD4+ CD45RA+ Foxp3- CD25- populations (199 days). However, the regulatory population was susceptible to apoptosis and had critically short telomeres and low telomerase activity. It was therefore unlikely to be self regenerating. These data are consistent with continuous production from another population source. We found extremely close TCR clonal homology between regulatory and memory CD4+ T cells. Furthermore, antigen-related expansions within certain TCR Vbeta families were associated with parallel numerical increases of CD4+ CD45RO+ CD25hi Foxp3+ Tregs with the same Vbeta usage. It is therefore unlikely that all human CD4+ CD25+ Foxp3+ Tregs are generated as a separate functional lineage in the thymus. Instead, our data suggest that a proportion of this regulatory population is generated from rapidly dividing, highly differentiated memory CD4+ T cells; this has considerable implications for the therapeutic manipulation of these cells in vivo.     

Reversal of airway hyperresponsiveness by induction of airway mucosal CD4+CD25+ regulatory T cells

An important feature of atopic asthma is the T cell-driven late phase reaction involving transient bronchoconstriction followed by development of airways hyperresponsiveness (AHR). Using a unique rat asthma model we recently showed that the onset and duration of the aeroallergen-induced airway mucosal T cell activation response in sensitized rats is determined by the kinetics of functional maturation of resident airway mucosal dendritic cells (AMDCs) mediated by cognate interactions with CD4+ T helper memory cells. The study below extends these investigations to chronic aeroallergen exposure. We demonstrate that prevention of ensuing cycles of T cell activation and resultant AHR during chronic exposure of sensitized rats to allergen aerosols is mediated by CD4+CD25+Foxp3+LAG3+ CTLA+CD45RC+ T cells which appear in the airway mucosa and regional lymph nodes within 24 h of initiation of exposure, and inhibit subsequent Th-mediated upregulation of AMDC functions. These cells exhibit potent regulatory T (T reg) cell activity in both in vivo and ex vivo assay systems. The maintenance of protective T reg activity is absolutely dependent on continuing allergen stimulation, as interruption of exposure leads to waning of T reg activity and reemergence of sensitivity to aeroallergen exposure manifesting as AMDC/T cell upregulation and resurgence of T helper 2 cytokine expression, airways eosinophilia, and AHR.     

类风湿性关节炎患者外周血CD4^＋CD25^＋调节性T细胞的表达及意义

CD4 CD25 调节性T细胞是一种除主要表达CD25分子外,还表达CTLA-4和G ITR(糖皮质激素诱导的TNF受体)等的CD4 T细胞亚群,它不但是参与对自身抗原外周耐受的主要T细胞群,而且还作为对外来抗原应答的调节性T细胞,对于维持外周免疫耐受有重要意义[1,2]。已有研究表明,自身免疫病的易     

脓毒症患儿CD4+CD25+调节性T细胞的变化

目的 观察不同免疫状态下脓毒症婴幼儿外周血CD4+CD25+Foxp3high调节性T细胞(Treg细胞)及相关分子的变化,探讨婴幼儿脓毒症免疫功能紊乱的可能机制.方法 分别收集2007年5月至2007年11月深圳市儿童医院重症监护室收治的婴幼儿脓毒症36例血液标本,另选16例健康同龄儿童作为正常对照进行前瞻性研究;排除既往患有自身免疫性疾病、免疫缺陷病、遗传代谢病及肿瘤的患儿,排除近6个月曾使用影响免疫功能的药物.本研究获得深圳市儿童医院伦理委员会的同意.以外周血CD14+单核细胞HLA-DR表达>30%或<30%为阈值,将患儿分为免疫激活组(DR-H组)和免疫抑制组(DR-L组),用流式细胞术检测CD14+单核细胞HLA-DR表达率,CD4+CD25+Foxp3highTreg细胞比例;实时荧光定量PCR(Real time-PCR)检测CD4+T细胞Foxp3、CTLA-4、GITR、IL-10mRNA表达.统计方法采用单因素方差分析,P<0.05为差异具有统计学意义.结果 急性期DR-L组CD4+CD25+Foxp3highTreg细胞比例明显高于对照组及DR-H组(P<0.05).DR-L组Foxp3、CTLA-4、IL-10等相关分子基因表达高于对照组及DR-H组(P<0.05),DR-L组GITR基因表达高于DR-H组.结论 CD4+CD25+Foxp3highTreg细胞数量异常增加可能与婴幼儿脓毒症免疫抑制状态有关.     

CD4~+CD25~+调节性T细胞的一般特性及其在银屑病发病中的作用

CD4+CD25+调节性T细胞是一组具有免疫调节作用的T细胞群,对于维持机体免疫耐受和免疫应答稳态具有非常重要的作用。越来越多的研究表明,银屑病是多基因遗传背景下T细胞介导的免疫性疾病,CD4+CD25+调节性T细胞的免疫反应及其分泌的细胞因子在银屑病的发病中有着重要作用。本文主要就CD4+CD25+调节性T细胞的一般特性及其在银屑病发病机制中作用的研究进展作一综述,帮助我们更深入地了解银屑病的发病机制并为今后临床诊断和治疗提供依据。     

CD4+CD25+ T(R) cells suppress innate immune pathology through cytokine-dependent mechanisms

CD4(+)CD25(+) regulatory T (T(R)) cells can inhibit a variety of autoimmune and inflammatory diseases, but the precise mechanisms by which they suppress immune responses in vivo remain unresolved. Here, we have used Helicobacter hepaticus infection of T cell-reconstituted recombination-activating gene (RAG)(-/-) mice as a model to study the ability of CD4(+)CD25(+) T(R) cells to inhibit bacterially triggered intestinal inflammation. H. hepaticus infection elicited both T cell-mediated and T cell-independent intestinal inflammation, both of which were inhibited by adoptively transferred CD4(+)CD25(+) T(R) cells. T cell-independent pathology was accompanied by activation of the innate immune system that was also inhibited by CD4(+)CD25(+) T(R) cells. Suppression of innate immune pathology was dependent on T cell-derived interleukin 10 and also on the production of transforming growth factor beta. Thus, CD4(+)CD25(+) T(R) cells do not only suppress adaptive T cell responses, but are also able to control pathology mediated by innate immune mechanisms.     

胃幽门螺杆菌感染与哮喘急性发作及CD4~+CD25~+T细胞的作用机制研究

目的探讨胃幽门螺杆菌(HP)感染与哮喘急性发作的关系及免疫机制,为更好地预防和治疗哮喘提供理论依据。方法 32例哮喘发作期和20例哮喘缓解期患儿通过14C尿素呼气试验(14C-UBT)检测HP感染情况,同时采集所有患儿及同期10例健康儿童外周静脉血,通过流式细胞仪测定CD4+CD25+调节性T细胞占CD4+T细胞的百分比。结果哮喘急性发作期患儿14C-UBT阳性率明显高于缓解期患儿(P<0.05);HP阳性哮喘患儿CD4+CD25+调节性T细胞水平显著低于HP阴性哮喘患儿及对照组;无论HP感染阳性还是阴性患儿,其哮喘发作期CD4+CD25+调节性T细胞水平均低于哮喘缓解期,且哮喘发作期HP阳性组CD4+CD25+调节性T细胞水平低于HP阴性组(P<0.05)。结论 HP感染可能是诱导哮喘急性发作的原因之一,HP感染后激发和加重了机体的免疫异常,进一步抑制了CD4+CD25+调节性T细胞的表达而不能有效发挥其免疫抑制功能,是哮喘急性发作的可能机制。