CD4+T细胞的研究进展

近年来,随着对CD4+T细胞研究的深入,对Th1和Th2细胞的免疫生物学活性及免疫调节也有了进一步的认识.CD4+T细胞新亚型CD4+CD25+调节性T细胞(Treg)及Th17细胞受到了人们广泛的关注,尤其是细胞的分化调节、功能及相关疾病的发病机制.本文就CD4+T细胞各亚群的生物学特征及分工、亚群间的相互调节、免疫应答与疾病的关系等作一综述.     

人胸腺和脐血造血干/祖细胞联合移植对裸鼠T细胞免疫功能影响

目的:建立人胸腺和脐血造血干/祖细胞联合移植裸鼠动物模型,探讨胸腺对造血干细胞发育分化的机制.方法:实验组为人胸腺与脐血CD34+细胞联合移植.对照组只给予人脐血CD34+细胞移植,通过观察裸鼠移植胸腺CD3、HLA-DR的表达、人源CD3+细胞在小鼠脾脏的表达、裸鼠血液CD3+、CD4+、CD8+和CD4+ CD25+细胞的百分比,以及联合移植裸鼠对移植肿瘤的排斥能力,判断联合移植对裸鼠免疫功能的影响.结果:移植胸腺在裸鼠肾被膜下存活,表达CD3和HLA-DR分子;裸鼠脾脏中检测到人源CD3+T细胞呈点块状分布;裸鼠血液中CD3+、CD4+、CD8+、CD4+CD25+细胞均增高,与对照组比较差异有统计学意义(P<0.05);联合移植组能抵抗肿瘤细胞的生长,单独脐血造血干/祖细胞移植组不能抑制肿瘤生长.结论:裸鼠移植人胸腺能促进人脐血造血干/祖细胞向T细胞分化、促进免疫功能重建.     

结核分枝杆菌感染者辅助性Th1型细胞因子水平变化

<正>结核分枝杆菌(Mycobacterium tuberculosis)是胞内感染菌,其免疫主要是以T细胞为主的细胞免疫。T淋巴细胞是高度异质性的群体,根据发育过程中出现的分化抗原的不同,分为CD4+T细胞和CD8+T细胞。1986年Mosmann等[1]根据小鼠的CD4+T细胞克隆产生细胞因子类型的不同,将CD4+T细胞分为T辅助性(Th1)和Th2两种类型,随后Romagnani等[2]证实体内存在相应的Th1和     

流式细胞术研究间充质干细胞对人Th1细胞的作用

本研究应用流式细胞术(FCM)探究胚胎骨髓来源的间充质干细胞(FBM-MSC)对人Th1细胞的作用。体外分离、培养、扩增人FBM-MSC,并对其进行免疫表型及分化潜能的鉴定。CD4+T细胞单独培养或与FBM-MSC共培养(FBM-MSC/CD4),通过FCM和酶联免疫吸附试验(ELISA)方法分别测定单独培养的CD4+T细胞和FBM-MSC/CD4中Th1细胞(干扰素-γ+)的数量。结果表明,FBM-MSC的免疫表型及分化潜能均符合间充质干细胞(MSC)的标准。FBM-MSC对Th1细胞的发育具有抑制作用。FCM检测发现,FBM-MSC/CD4中Th1细胞数量明显低于单独培养的CD4+T细胞。ELISA检测结果表明,IFN-γ的蛋白水平在FBM-MSC/CD4中亦低于单独培养的CD4+T细胞;同时,FBM-MSC/CD4中IL-6的表达水平明显高于单独培养的CD4+T细胞或FBM-MSC细胞中的水平。而IL-6中和抗体能够增加FBM-MSC/CD4中的Th1细胞数量和IFN-γ的水平。结论:FBM-MSC对人Th1细胞具有抑制作用,IL-6信号通路可能是该抑制作用的机制之一。     

Th17细胞在自身免疫疾病中的研究

自身免疫疾病是威胁人类健康的常见疾病之一。免疫系统异常是导致自身免疫疾病发生、进展和预后的关键。CD4+T细胞作为效应T细胞的重要成分,参与免疫应答的各个阶段,在免疫调节中发挥关键作用。经典免疫学将CD4+T细胞分为Th1和Th2两个亚群,两者在免疫应答反应过程中相互     

T细胞亚群及其细胞因子在噬血细胞性淋巴组织细胞增多症中的作用

噬血细胞性淋巴组织细胞增多症(HLH)又称噬血细胞综合征(HPS),是由多种病因导致的体内单核巨噬细胞过度增生活化并伴随其吞噬血细胞现象的综合征.本综合征常分为遗传性(FHL)和继发性(sHLH)两类.T淋巴细胞亚群主要包括CD4+和CD8+T细胞,而CD4+T细胞主要有Th1和Th2细胞.在FHL,CD8+T细胞的细胞毒功能受损,导致高细胞因子血症.在sHLH,Th1和Th2细胞失衡,特别是Th1细胞产生大量的细胞因子在HLH的发病中起着重要作用.本研究对T细胞亚群及其细胞因子在HLH发病机制中的作用进行综述.     

慢性肾小球肾炎患者外周血Th1/Th2及CD28~+细胞的变化及其临床意义

目的探讨慢性肾小球肾炎(CGN)患者外周血Th1/Th2及CD28+细胞百分率的变化在疾病进程中可能的细胞免疫学机制。方法采用流式细胞术检测50例CGN患者及30名正常人(对照组)外周血Th1/Th2和CD28+细胞的百分率,用SPSS 16.0软件对试验结果进行统计分析。结果与对照组比较,CGN患者外周血CD3+CD4+细胞百分率和CD4/CD8比值明显降低(P0.05),Th1和Th2细胞百分率差异无统计学意义(P0.05),但Th1/Th2比值明显增高(P0.05);CGN患者CD28+、CD4+CD28+细胞百分率明显减少(P均0.01)。结论 CGN患者体内T细胞免疫功能紊乱和活化受限,细胞免疫功能低下,Th1和Th2细胞失衡,通过对CGN患者外周血Th1/Th2及CD28+细胞的检测,有助于了解患者的细胞免疫状态,为临床诊断和免疫治疗提供参考依据。     

SLE患者T细胞亚群功能紊乱与Th1、Th2细胞因子偏移的研究

目的 :探讨系统性红斑狼疮 (SLE)患者细胞因子表达异常与细胞免疫功能紊乱的机制。方法 :用流式细胞仪根据直接免疫荧光法分别测定病例组与对照组T细胞表面标志CD3 ,CD4,CD8的表达情况。用微量反应板根据酶联免疫吸附测定法分别测定病例组与对照组血清IL - 2及IL - 6水平。结果 :SLE患者CD3 + CD4+ 细胞较正常对照组明显降低 (P <0 0 1) ,CD3 + CD8+ 细胞较正常对照组明显增加 (P <0 0 1) ,CD4+ T/CD8+ T细胞比例倒置 ;血清IL - 2水平较正常对照组明显降低 (P <0 0 1) ,而血清IL - 6水平较正常对照组明显增高 (P <0 0 5 )。结论 :SLE患者体内细胞免疫功能紊乱是介导免疫调节紊乱的主要因素 ,CD4+ T/CD8+ T细胞比例倒置 ,而CD4+ T细胞水平明显降低 ,其Th1,Th2细胞功能也表现明显偏移 ,以Th2细胞亢进为主 ,产生大量Th2细胞因子 ,介导免疫调节反应 ,致B淋巴细胞活跃产生大量自身抗体及免疫球蛋白。同时 ,CD8+ T细胞功能亢进 ,CTL细胞参与机体组织损伤 ,进一步导致免疫紊乱及免疫病理损伤加重     

中医疗法对过敏性紫癜患者免疫功能的调节作用

目的探讨以疏风清热、活血化瘀立法治疗过敏性紫癜(HSP)前后,外周血白细胞总数、淋巴细胞数、淋巴细胞亚群、辅助性T细胞(Th)1/Th2及调节性T细胞的变化。方法使用血细胞分析仪检测36例住院患者血常规,统计其中的白细胞总数及淋巴细胞数。使用流式细胞仪检测36例住院患者外周血淋巴细胞亚群、Th1/Th2及调节性T细胞。结果 HSP患者治疗后(恢复期)与治疗前(急性期)相比较,白细胞数、淋巴细胞数、CD3~+、CD4~+、CD19~+降低(P0.05),CD8~+、CD16~+CD56~+、Th1/Th2、CD4~+CD25~+升高(P0.05);HSP患者治疗前与对照组相比较,白细胞数、淋巴细胞数、CD3~+、CD4~+、CD19~+明显升高(P0.05),CD8~+、CD16~+CD56~+、Th1/Th2、CD4~+CD25~+降低(P0.05);HSP患者治疗后与对照组相比较,白细胞数、淋巴细胞数、CD19~+升高(P0.05);CD16~+降低(P0.05);CD3~+、CD4~+、CD8~+、Th1/Th2、CD4~+CD25~+无差异(P0.05)。结论以疏风清热、活血化瘀立法治疗HSP,能明显干预患者的外周血白细胞总数、淋巴细胞数、淋巴细胞亚群、Th1/Th2及调节性T细胞,对患者的免疫功能的调节作用明确,临床效果显著,极大地提高了临床诊疗能力。     

CD4+CD25+调节性T细胞免疫抑制作用机制的研究进展

CD4+CD25+调节性T细胞是一群具有免疫抑制作用的负性调控细胞,在人体自身免疫、维持免疫系统稳态及许多疾病中发挥重要作用.目前有关CD4+CD25+调节性T细胞分化发育的确切机制及行使功能的作用机制尚不清楚.本文就其免疫抑制作用机制的研究进展作一综述.     

Immunological abnormalities in human immunodeficiency virus (HIV)-infected asymptomatic homosexual men. HIV affects the immune system before CD4+ T helper cell depletion occurs.

To investigate the effect of persistent HIV infection on the immune system, we studied leukocyte functions in 14 asymptomatic homosexual men (CDC group II/III) who were at least two years seropositive, but who still had normal numbers of circulating CD4+ T cells. Compared with age-matched heterosexual men and HIV-negative homosexual men, the CD4+ and CD8+ T cells from seropositive men showed decreased proliferation to anti-CD3 monoclonal antibody and decreased CD4+ T-helper activity on PWM-driven differentiation of normal donor B cells. Monocytes of HIV-infected homosexual men showed decreased accessory function on normal T cell proliferation induced by CD3 monoclonal antibody. The most striking defect in leukocyte functional activities was observed in the B cells of HIV-infected men. B cells of 13 out of 14 seropositive men failed to produce Ig in response to PWM in the presence of adequate allogeneic T-helper activity. These findings suggest that HIV induces severe immunological abnormalities in T cells, B cells, and antigen-presenting cells early in infection before CD4+ T cell numbers start to decline. Impaired immunological function in subclinically HIV-infected patients may have clinical implications for vaccination strategies, in particular the use of live vaccines in groups with a high prevalence of HIV seropositivity.     

Significant immunomodulatory effects of Pseudomonas aeruginosa quorum-sensing signal molecules: possible link in human sepsis

Pathogenic bacteria use quorum-sensing signal molecules to co-ordinate the expression of virulence genes. Animal-based studies have demonstrated the immunomodulatory effects of quorum-sensing signal molecules. In the present study, we have examined the impact of these molecules on normal human immune function in vitro and compared this with immune changes in patients with sepsis where quorum-sensing signal molecules were detected in the sera of patients. Quorum-sensing signal molecules inhibited normal dendritic cell and T-cell activation and proliferation, and down-regulated the expression of co-stimulatory molecules on dendritic cells; in MLDCRs (mixed lymphocyte dendritic cell reactions), secretion of IL (interleukin)-4 and IL-10 was enhanced, but TNF-alpha (tumour necrosis factor-alpha), IFN-gamma (interferon-gamma) and IL-6 was reduced. Quorum-sensing signal molecules induced apoptosis in dendritic cells and CD4(+) cells, but not CD8(+) cells. Dendritic cells from patients with sepsis were depleted and ex vivo showed defective expression of co-stimulatory molecules and dysfunctional stimulation of allogeneic T-lymphocytes. Enhanced apoptosis of dendritic cells and differential CD4(+) Th1/Th2 (T-helper 1/2) cell apoptotic rate, and modified Th1/Th2 cell cytokine profiles in MLDCRs were also demonstrated in patients with sepsis. The pattern of immunological changes in patients with sepsis mirrors the effects of quorum-sensing signal molecules on responses of immune cells from normal individuals in vitro, suggesting that quorum-sensing signal molecules should be investigated further as a cause of immune dysfunction in sepsis.     

Perforin and Fas killing by CD8+ T cells limits their cytokine synthesis and proliferation

During an immune response, effector CD8+ T cells can kill infected cells by the perforin-dependent pathway. In comparison to CD4+ T cells, which are major sources of cytokines, normal CD8+ T cells produced less interleukin 2 and interferon gamma, and proliferated less vigorously after antigenic stimulation. Killing of target cells was a major cause of these reduced responses, since perforin-deficient CD8+ T cells showed substantially increased cytokine synthesis and proliferation. Cytotoxicity by the alternate Fas pathway also resulted in self- limitation of CD8+ T cell cytokine synthesis. This relationship between cytotoxicity and cytokine synthesis may regulate CD8+ T function in different phases of an immune response.     

胚胎骨髓来源间充质干细胞对人Th17细胞的免疫调节

背景:众多研究表明间充质干细胞能发挥免疫调节功能,抑制T细胞增殖。目的:观察胚胎骨髓来源间充质干细胞对人Th17细胞的调节作用。方法:将人胚胎骨髓间充质干细胞与正常人外周血单个核细胞或CD4+T细胞以1∶10比例共培养4d,以单个核细胞或CD4+T细胞单独培养为对照。应用实时定量PCR检测细胞白细胞介素17mRNA表达,酶联免疫吸附试验检测细胞上清中白细胞介素17蛋白水平,流式细胞术检测Th17细胞数量。结果与结论:胚胎骨髓来源间充质干细胞与单个核细胞共培养组白细胞介素17mRNA表达水平明显高于单个核细胞组(P<0.01)。与此一致的是,胚胎骨髓来源间充质干细胞与单个核细胞或CD4+T细胞共培养组细胞上清中白细胞介素17蛋白水平明显高于单个核细胞组、CD4+T细胞组(P<0.05,P<0.01)。胚胎骨髓来源间充质干细胞与CD4+T细胞共培养组Th17细胞数量明显高于CD4+T细胞组(P<0.01),但胚胎骨髓来源间充质干细胞本身并不表达白细胞介素17。表明胚胎骨髓来源间充质干细胞可促进人Th17细胞增殖。     

A new device for selective removal of CD4+ T cells.

To control antigen (Ag)-specific immune cells is important in the treatment of autoimmune diseases. In particular, a direct solution may be obtained by controlling the CD4+ cell function that controls the immune response of autoimmune T cells. Thus, a technique to selectively remove CD4+ cells has been developed, based on the consideration that the immune system may possibly be modified by selectively removing the CD4+ cells by means of extracorporeal circulation. The currently developed device to selectively remove CD4+ cells uses a material made of nonwoven fabric with monoclonal antibodies immobilized on the surface. With this device, removal of only CD4+ cells from human mononuclear cells suspension can be accomplished. Moreover, CD4+ cells can be specifically removed from peripheral whole blood by direct perfusion. This review outlines a series of procedures for selective cell removal and the results of our research.     

Adoptive transfer of lymphocytes sensitized to the major surface glycoprotein of Pneumocystis carinii confers protection in the rat.

Pneumocystis carinii is a major opportunistic pathogen and a leading cause of morbidity in patients with AIDS. CD4+ cells have been shown to be important in host defenses against P. carinii, but the antigen(s) involved with this response have not been identified. We undertook the present study to determine whether the major surface glycoprotein (MSG) of P. carinii contains epitopes that can elicit a protective cellular immune response. Spleen cells and purified CD4+ cells isolated from Lewis rats, pulsed 1-4 d with MSG, and injected into corticosteroid-treated Lewis rats with pneumocystosis resulted in significant reduction in the P. carinii burden, as judged by organism quantitation and lung histology. The protective response demonstrated by the donor cells was dependent on previous exposure to P. carinii, cell concentration, and time of incubation with MSG. In addition, reconstitution with MSG-specific CD4+ cells resulted in an early hyperinflammatory response within the lungs of these animals with a high percentage of mortality. Thus, in this model, MSG can elicit an immune response mediated by CD4+ cells, which has a harmful as well as helpful effect on the host, and these responses occur despite the presence of corticosteroids.     

Lack of Leu-3a epitope on T-helper (CD4) lymphocytes.

Human T-helper cells express membrane-bound CD4 antigen whose many epitopes are recognized by different monoclonal antibodies. The epitope recognized by Leu-3a and similar clones has been shown to be the location for human immunodeficiency virus (HIV) receptor. We have found a unique blood donor whose CD4+ T-helper lymphocytes were lacking Leu-3a epitope. CD4+ T-helper cells lacking Leu-3a epitope might be resistant to HIV infection.     

Phenotypic and functional lymphocyte recovery after CD34+-enriched versus non-T cell-depleted autologous peripheral blood stem cell transplantation

To determine the effect of CD34+ selection on immune recovery after high-dose chemo/radiotherapy in the setting of autologous stem cell transplantation (ASCT), we analyzed quantitative and qualitative lymphocyte reconstitution for up to 1 year post-transplantation in 27 consecutive adult patients receiving either CD34+-enriched or unmanipulated autologous stem cell (SC) grafts. Pretransplant immunological parameters were identical for both treatment groups. Total lymphocyte counts as well as CD3+ T cells provided a similar course of recovery in both cohorts, returning to baseline values within the first 3 months. There were no significant differences in the reconstitution kinetics of CD4+, CD8+, CD45RA+, and CD45RO+ T cells. CD4+ and CD45RA+ T cells between the two groups were significantly decreased within the first 6 months, returning to pretransplant baseline values by 1 year. Although within the first 3 months the majority of CD3+ cells were activated as demonstrated by expression of HLA-DR, we observed a significant loss of CD25+ T cells in both groups within the first 6 months. B cell numbers returned to baseline values within 3 months but in vivo B cell function measured by serum immunoglobulin M (IgM) and IgA levels did not recover as early as 6 months post-transplantation. T cell function measured by proliferation in response to the lectins phytohemagglutinin (PHA) and Concanavalin A (ConA) and to alloantigens in the mixed lymphocyte reaction (MLR) was significantly impaired, but tended to return to pretransplant baseline values by 1 year. Although preliminary, our results provide strong evidence that T cell depletion (TCD) by CD34+ enrichment using the CellPro device does not result in delayed phenotypic immune reconstitution after autologous peripheral blood stem cell transplantation (PB-SCT). Even in the absence of a high thymic T cell regenerative capacity in adults, T cell numbers and subset distributions were restored within the time frame studied. T and B cell function, however, remained significantly impaired for a prolonged period of time (>6 months after SCT) with a more profound defect in patients autografted with CD34+-enriched SC.     

Critical role of EBNA1-specific CD4+ T cells in the control of mouse Burkitt lymphoma in vivo

CD4+ T cells play important roles in orchestrating host immune responses against cancer and infectious diseases. Although EBV-encoded nuclear antigen 1-specific (EBNA1-specific) CD4+ T cells have been implicated in controlling the growth of EBV-associated tumors such as Burkitt lymphoma (BL) in vitro, direct evidence for their in vivo function remains elusive due to the lack of an appropriate experimental BL model. Here, we describe the development of a mouse EBNA1-expressing BL tumor model and the identification of 2 novel MHC H-2I-A(b)-restricted T cell epitopes derived from EBNA1. Using our murine BL tumor model and the relevant peptides, we show that vaccination of mice with EBNA1 peptide-loaded DCs can elicit CD4+ T cell responses. These EBNA1-specific CD4+ T cells recognized peptide-pulsed targets as well as EBNA1-expressing tumor cells and were necessary and sufficient for suppressing tumor growth in vivo. By contrast, EBNA1 peptide-reactive CD8+ T cells failed to recognize tumor cells and did not contribute to protective immunity. These studies represent what we believe to be the first demonstration that EBNA1-specific CD4+ T cells can suppress tumor growth in vivo, which suggests that CD4+ T cells play an important role in generating protective immunity against EBV-associated cancer.     

Exosomal-like vesicles with immune-modulatory features are present in human plasma and can induce CD4+ T-cell apoptosis in vitro

BACKGROUND: Exosomes are small membrane vesicles that are secreted from many cell types into various body fluids. These vesicles are thought to play a role in cell–cell interactions. STUDY DESIGN AND METHODS: Vesicles were isolated from human plasma of healthy donors by differential ultracentrifugation and ultrafiltration. The vesicles were identified by transmission electron microscopy, and their biochemical characteristics were analyzed by Western blot and flow cytometry. The immune‐modulatory ability of exosomal‐like vesicles was examined by incubating them with CD4+ T cells for CD4+ T‐cell proliferation and apoptosis assays in vitro. RESULTS: Vesicles purified from human plasma displayed shapes and sizes similar to those of previously described exosomes and contained exosomes marker proteins CD63 and CD81. They also expressed molecules such as MHC Class II molecules, CD80, CD86, and the cell signal transduction molecules Wnt3a, Wnt5a, and FasL. Furthermore, functional analysis showed that allogeneic plasma exosomes restrained the survival of CD4+ T cells. Plasma exosomes can induce dose‐dependent suppression of proliferation of activated CD4+ T cells, with the strongest responses induced by 500 µg/mL exosomes in vitro. Antibodies against exosomes FasL can block the activity of exosomes on CD4+ T‐cell apoptosis. Moreover, three different concentrations of CD4+ T cells were inhibited by plasma exosomes and the suppressive function was not dependent on interleukin‐2. CONCLUSION: Exosomes present in human plasma contain immunity‐associated molecules and can induce CD4+ T‐cell apoptosis in vitro. Plasma exosomes have the capacity to influence immune responses.