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.     

Anti-idiotypic monoclonal antibodies (mAb) to an anti-CD4 mAb induce CD4+ T cell depletion in rabbit

Summary We previously produced and characterized the syngeneic anti-idiotypic (Ab2) mAb F11-2302, F16-14D6 and F16-16D7 elicited with the mouse anti-human CD4 mAb HP2/6. We showed that F11-2302, which reacts with an idiotope (id) outside the antigen (Ag) combining site, fails to induce anti-CD4 antibodies (Ab) in mice, whereas mAb F16-14D6 and F16-16D7 to an id within (or closely related to) mAb HP2/6 Ag-combining site induces Ab to CD4 molecule. In the present investigation we extended our analysis to the immune response induced by these three mAb in a xenogeneic system by immunizing three New Zealand White (NZW) rabbits with Ab2 mAb. The latter animals were selected since rabbit CD4 molecules displayed a weak cross-reactivity with the anti-human CD4 mAb HP2/6. An additional rabbit was not immunized and used, together with the F11-2302-immunized one, as control. The three rabbits developed Ab3 Ab highly restricted to their respective immunizing mAb. Although no Ab reacting with human CD4 were detected in the three affinity-purified Ab3 preparations, a marked decrease in the percentage of CD4⁺ T cells was observed in the rabbits immunized with mAb F16-14D6 and F16-16D7. The results suggest that active specific immunotherapy with selected Ab2 mAb may induced biological effects similar to those generated by the passive administration of anti-CD4 mAb, and the rabbit could be an appropriate xenogeneic host for the testing of potential applications of anti-CD4 Ab2 mAb active immunotherapy in transplantation and autoimmune diseases.     

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.     

Conferring indirect allospecificity on CD4+CD25+ Tregs by TCR gene transfer favors transplantation tolerance in mice

T cell responses to MHC-mismatched transplants can be mediated via direct recognition of allogeneic MHC molecules on the cells of the transplant or via recognition of allogeneic peptides presented on the surface of recipient APCs in recipient MHC molecules - a process known as indirect recognition. As CD4(+)CD25(+) Tregs play an important role in regulating alloresponses, we investigated whether mouse Tregs specific for allogeneic MHC molecules could be generated in vitro and could promote transplantation tolerance in immunocompetent recipient mice. Tregs able to directly recognize allogeneic MHC class II molecules (dTregs) were obtained by stimulating CD4(+)CD25(+) cells from C57BL/6 mice (H-2(b)) with allogeneic DCs from BALB/c mice (H-2(d)). To generate Tregs that indirectly recognized allogeneic MHC class II molecules, dTregs were retrovirally transduced with TCR genes conferring specificity for H-2K(d) presented by H-2A(b) MHC class II molecules. The dual direct and indirect allospecificity of the TCR-transduced Tregs was confirmed in vitro. In mice, TCR-transduced Tregs, but not dTregs, induced long-term survival of partially MHC-mismatched heart grafts when combined with short-term adjunctive immunosuppression. Further, although dTregs were only slightly less effective than TCR-transduced Tregs at inducing long-term survival of fully MHC-mismatched heart grafts, histologic analysis of long-surviving hearts demonstrated marked superiority of the TCR-transduced Tregs. Thus, Tregs specific for allogeneic MHC class II molecules are effective in promoting transplantation tolerance in mice, which suggests that such cells have clinical potential.     

CD4+CD25+和CD8+调节性T细胞的作用机制

调节性T细胞（Treg）主要在机体免疫系统中发挥负向调节作用,既能抑制不恰当的免疫反应,又能限定免疫应答的范围、程度及作用时间,对CD4^＋和CD8^＋效应性T淋巴细胞的增殖起抑制作用,因此在移植物抗宿主病、自身免疫病、过敏性疾病等的发病机制和临床治疗中有潜在的应用价值.本文重点介绍CD4^＋CD25^＋Treg和CD8^＋Treg的作用机制,并简述调节性T细胞研究面临的挑战与展望.     

Role of IFN-gamma in induction of Foxp3 and conversion of CD4+ CD25- T cells to CD4+ Tregs

IFN-gamma is an important Th1 proinflammatory cytokine and has a paradoxical effect on EAE in which disease susceptibility is unexpectedly heightened in IFN-gamma-deficient mice. In this study, we provide what we believe is new evidence indicating that IFN-gamma is critically required for the conversion of CD4+ CD25- T cells to CD4+ Tregs during EAE. In our study, the added severity of EAE in IFN-gamma knockout mice was directly associated with altered encephalitogenic T cell responses, which correlated with reduced frequency and function of CD4+ CD25+ Foxp3+ Tregs when compared with those of WT mice. It was demonstrated in both human and mouse systems that in vitro IFN-gamma treatment of CD4+ CD25- T cells led to conversion of CD4+ Tregs as characterized by increased expression of Foxp3 and enhanced regulatory function. Mouse CD4+ CD25- T cells, when treated in vitro with IFN-gamma, acquired marked regulatory properties as evidenced by suppression of EAE by adoptive transfer. These findings have important implications for the understanding of the complex role of IFN-gamma in both induction and self regulation of inflammatory processes.     

抗CD3单克隆抗体对人CD4^＋CD25^＋T淋巴细胞凋亡和自噬的影响

目的观察抗CD3单克隆抗体对分离培养的人外周血CD4^＋CD25^＋T淋巴细胞自噬、凋亡及其分泌的代表性因子转化生长因子β（TGF-β）的影响。方法采用密度梯度离心法及尼龙棉柱法分离32例健康者外周血T淋巴细胞,磁性细胞分离器（MACS）分离得到CD4^＋CD25^＋T淋巴细胞,分别利用电镜及流式细胞仪观察、检测各组（抗CD3单克隆抗体1mg/L组、IgG1同型抗体对照组）干预72h后细胞的凋亡率、自噬率,用ELISA法检测细胞培养上清液中细胞因子TGF-β的水平。结果抗CD3单克隆抗体组CD4^＋CD25^＋T淋巴细胞自噬率、凋亡率及TGF-β水平均增加（均P〈0.01）,凋亡率和自噬率之间无相关性（P〉0.05）。结论抗CD3单克隆抗体可促进CD4^＋CD25^＋T淋巴细胞凋亡和自噬及TGF-β分泌,且自噬与凋亡间相互独立。     

Intravaginal immunization with HPV vectors induces tissue-resident CD8+ T cell responses

The induction of persistent intraepithelial CD8⁺ T cell responses may be key to the development of vaccines against mucosally transmitted pathogens, particularly for sexually transmitted diseases. Here we investigated CD8⁺ T cell responses in the female mouse cervicovaginal mucosa after intravaginal immunization with human papillomavirus vectors (HPV pseudoviruses) that transiently expressed a model antigen, respiratory syncytial virus (RSV) M/M2, in cervicovaginal keratinocytes. An HPV intravaginal prime/boost with different HPV serotypes induced 10-fold more cervicovaginal antigen-specific CD8⁺ T cells than priming alone. Antigen-specific T cell numbers decreased only 2-fold after 6 months. Most genital antigen-specific CD8⁺ T cells were intra- or subepithelial, expressed α_E-integrin CD103, produced IFN-γ and TNF-α, and displayed in vivo cytotoxicity. Using a sphingosine-1-phosphate analog (FTY720), we found that the primed CD8⁺ T cells proliferated in the cervicovaginal mucosa upon HPV intravaginal boost. Intravaginal HPV prime/boost reduced cervicovaginal viral titers 1,000-fold after intravaginal challenge with vaccinia virus expressing the CD8 epitope M2. In contrast, intramuscular prime/boost with an adenovirus type 5 vector induced a higher level of systemic CD8⁺ T cells but failed to induce intraepithelial CD103⁺CD8⁺ T cells or protect against recombinant vaccinia vaginal challenge. Thus, HPV vectors are attractive gene-delivery platforms for inducing durable intraepithelial cervicovaginal CD8⁺ T cell responses by promoting local proliferation and retention of primed antigen-specific CD8⁺ T cells.     

慢性乙型肝炎患者外周血CD8+CD25+FoxP3+调节性T细胞比例的变化及临床意义

目的 探讨外周血CD8+CD25+FoxP3+调节性T细胞(Treg)比例在慢性乙型肝炎(CHB)患者中的变化及临床意义.方法 选取2018年3-11月在滨海县第二人民医院传染科诊治的无症状乙型肝炎病毒(HBV)携带者28例为携带组,CHB患者28例为CHB组.同时选取28例年龄、性别匹配的健康体检者作为对照组.采用流...     

严重多发伤患者外周血中CD4^＋CD25^＋调节T细胞的变化特点

目的观察严重多发伤患者早期SIRS中CD4^＋CD25^＋调节T细胞（CD4^＋CD25^＋Treg）比例的变化，并探讨其与患者继发感染之间的关系。方法对符合SIRS诊断标准的23名严重多发伤患者，于确诊后的24h内无菌抗凝抽取静脉血，用流式细胞仪技术检测CD4^＋CD25^＋Treg的比例及CD4／CD8的比值，同时留取细胞培养，以嗜银染技术观察患者外周血淋巴细胞核仁形成区银染蛋白（Ag—NORs）的量，以核仁银染面积与核面积的比值（IS％）表示，了解淋巴细胞的增殖情况。并对入选患者于诊断成立的第1、5天留取痰、分泌物等标本行细菌学培养，观察患者的情况。结果符合SIRS的严重多发伤患者早期即有CD4^＋CD25^＋Treg比例的显著升高。并有IS％及CD4／CD8显著下降，和对照组相比，均有P〈0．01。CD4’CD25’Treg比例升高愈显著者，继发感染机率愈高。结论检测CD4^＋CD25^＋Treg的水平对于评估严重多发伤患者的细胞免疫状态，预测继发感染均有很大的帮助。     

CD3+CD16+NK1.1+B220+ large granular lymphocytes arise from both alpha- beta TCR+CD4-CD8- and gamma-delta TCR+CD4-CD8- cells

Cultivation of CD4-CD8- double negative (DN) mouse thymocytes and splenocytes with recombinant interleukin 2 (IL2) in the absence of other stimulation results in the generation of DN- CD3/TCR+CD16+NK1.1+B220+ large granular lymphocytes (LGL). Purified DN alpha-beta TCR+ thymocytes and splenocytes are CD16+IL2R alpha-IL2R beta+NK1.1+B220-CD5high. These cells are unique in that they express both CD16 and T cell receptor (TCR) which are usually mutually exclusive. In addition, they express the natural killer (NK) marker, NK1.1. Cultivation of these cells with IL2 for several days results in the generation of DN alpha-beta TCR+CD16+NK1.1+B220+CD5- LGL, suggesting that DN alpha-beta TCR+ cells in thymus and spleen are the precursors of the DN LGL reported previously. DN gamma-delta TCR+CD16- NK1.1-B220-CD5high thymocytes and splenocytes also give rise to DN gamma-delta TCR+CD16+NK1.1+B220+CD5- LGL which, as shown previously with DN alpha-beta TCR+ LGL cells, are cytotoxic against NK-sensitive YAC-1 cells. Cytotoxic activity is also induced through either CD16 or the gamma-delta TCR. DN alpha-beta TCR+ and DN gamma-delta TCR+ LGL cells are thus similar in phenotype to TCR- NK cells. DN alpha-beta TCR+ thymocytes express low levels of the gamma subunit of the high affinity immunoglobulin E receptor (Fc epsilon RI gamma) molecule, an essential component of CD16 expression. Fc epsilon RI gamma expression is greatly enhanced after cultivation with IL2, resulting in a higher surface expression of CD16. In contrast to DN alpha-beta TCR+ thymocytes, DN gamma-delta TCR+ thymocytes do not express detectable CD16 or Fc epsilon RI gamma mRNA but expression of both is induced by cultivation with IL2, leading to the expression of CD16 on the surface. Whereas CD16 molecules on both DN alpha-beta TCR+ and DN gamma-delta TCR+ LGL are associated with only Fc epsilon RI gamma homodimers, the TCR on these cells are associated with an Fc epsilon RI gamma homodimer and/or CD3 zeta-Fc epsilon RI gamma heterodimers. These results demonstrate that the Fc epsilon RI gamma subunit is a component of the TCR in a fraction of T lineage cells.     

CD4~＋ CD25~＋细胞和CD8~＋ CD28~-调节性T细胞在原发性肝癌患者外周血中的水平变化

目的研究原发性肝癌（HCC）患者外周血中CD4＋ CD25＋细胞和CD8＋ CD28-调节性T细胞的表达及意义。方法采用流式细胞仪测定93例HCC患者和24名健康人外周血中的CD4＋ CD25＋细胞和CD8＋ CD28-调节性T细胞水平。结果 HCC患者外周血中的CD4＋ CD25＋细胞[（14.39±4.58）%]和CD8＋ CD28-调节性T细胞[（24.05±5.64）%]表达均显著高于对照组[（8.37±1.73）%、（15.93±4.84）%,P〈0.05];CD8＋CD28-调节性T细胞与HCC的分期呈正相关（r=0.463,P〈0.001）。结论 CD4＋ CD25＋细胞和CD8＋ CD28-调节性T细胞在HCC患者外周血中呈高表达,且CD8＋ CD28-调节性T细胞与HCC的病情及预后相关。     

CD8+ T cell tolerance and cancer immunotherapy

To provide protection against all foreign pathogens one can possibly encounter during their lifetime, the T cell repertoire has to be as diverse as possible. At the same time, it is desirable that the T cell repertoire remains unresponsive towards healthy tissues. To realize this self/nonself discriminatory property, T cells undergo tightly controlled selection processes during maturation in the thymus. The key parameter determining the outcome of these selection processes is the avidity of the T cells for self-MHC/self-peptide complexes expressed in the thymus; low avidity interactions result in positive selection, whereas high avidity interactions lead to negative selection. Despite the selection processes, self-tolerance is far from absolute. In many cases, this is due to the presence of self-antigen in the thymus at a level that is too low to induce thymic deletion. In addition, T cells with a low avidity for ubiquitously expressed self-antigens can escape clonal deletion and enter the periphery. A thorough understanding of the self-specific T cell repertoire is important because many potential targets for cancer immunotherapy are self-proteins. In this review, the authors discuss the impact of self-antigen expression on the CD8+ T cell repertoire. An overview of the fate and functional capacities of self-specific T cells with specificity for tissue-restricted self-antigens and for ubiquitously expressed self-antigens is provided. Furthermore, the authors discuss the influence of negative selection on the antitumor reactivity of the mature T cell repertoire.     

苦豆子总碱对大鼠实验性结肠炎CD4+CD25+,CD8+CD28-表达的影响

目的:观察苦豆子总碱对实验性结肠炎大鼠的外周血和结肠组织中调节性T细胞CD4 CD25 ,CD8 CD28-表达的影响。方法:实验于2006-03/08在南方医科大学实验室进行。①分组:将72只SD大鼠数字表法随机分成正常对照组,模型组,5-氨基水杨酸组,苦豆子15,30,60mg/kg组共6组,每组12只。②造模:除正常对照组外,其他5组采用三硝基苯磺酸灌肠法制备结肠炎大鼠模型,正常对照组给予等量生理盐水灌肠。③给药:造模第2天开始灌胃给药,2mL/只,1次/d。5-氨基水杨酸组灌胃5-氨基水杨酸400mg/kg,苦豆子15,30,60mg/kg组灌胃酸苦豆子总碱15,30,60mg/kg,其他2组灌等量生理盐水。④取材:在第1周和第3周各组分别取6只大鼠处死,测定结肠黏膜组织和外周血中CD4 CD25 ,CD8 CD28-的表达水平,观察苦豆子总碱对模型大鼠急慢性期T细胞亚群的影响。结果:72只大鼠进入结果分析。①建模第1周:模型组结肠内T细胞亚群CD4 CD25 ,CD4 CD25 /CD25-,CD8 CD28-及CD8 CD28-/CD28 高于正常对照组(P<0.05,0.01),苦豆子各剂量组数据虽低于模型组,但经统计学处理后差异不显著(P>0.05)。②建模第3周:模型组大鼠外周血中的CD8 CD28-和CD8 CD28-/CD28 的表达高于正常对照组和苦豆子30,60mg/kg组[CD8 CD28-:(11.3±1.3)%,(5.4±2.2)%,(5.8±3.2)%,(6.0±4.2)%;CD8 CD28-/CD28 :(1.2±0.8)%,(0.4±0.1)%,(0.5±0.2)%,(0.5±0.4)%;P<0.05,0.01];结肠组织中的CD8 CD28-和CD8 CD28-/CD28 的表达也高于正常对照组和苦豆子30,60mg/kg组[CD8 CD28-:(17.4±4.2)%,(3.8±4.5)%,(3.9±4.0)%,(4.2±3.6)%;CD8 CD28-/CD28 :(1.8±0.3)%,(0.7±0.3)%,(0.7±0.2)%,(0.7±0.3)%;P<0.05,0.01]。结论:苦豆子总碱30,60mg/kg能下调实验性结肠炎大鼠慢性期高表达的CD8 CD28-T细胞。     

NVX-CoV2373 vaccination induces functional SARS-CoV-2–specific CD4+ and CD8+ T cell responses

NVX-CoV2373 is an adjuvanted recombinant full-length SARS-CoV-2 spike trimer protein vaccine demonstrated to be protective against COVID-19 in efficacy trials. Here we demonstrate that vaccinated individuals made CD4⁺ T cell responses after 1 and 2 doses of NVX-CoV2373, and a subset of individuals made CD8⁺ T cell responses. Characterization of the vaccine-elicited CD8⁺ T cells demonstrated IFN-γ production. Characterization of the vaccine-elicited CD4⁺ T cells revealed both circulating T follicular helper (cTfh) cells and Th1 cells (IFN-γ⁺, TNF-α⁺, and IL-2⁺) were detectable within 7 days of the primary immunization. Spike-specific CD4⁺ T cells were correlated with the magnitude of the later SARS-CoV-2–neutralizing antibody titers, indicating that robust generation of CD4⁺ T cells, capable of supporting humoral immune responses, may be a key characteristic of NVX-CoV2373 that utilizes Matrix-M adjuvant.     

Combined TLR and CD40 triggering induces potent CD8+ T cell expansion with variable dependence on type I IFN

Toll-like receptors are important in the activation of innate immunity, and CD40 is a molecule critical for many T and B cell responses. Whereas agonists for either pathway have been used as vaccine adjuvants, we show that a combination of Toll-like receptor (TLR)7 and CD40 agonists synergize to stimulate CD8+ T cell responses 10-20-fold greater than the use of either agonist alone. Antigen-specific CD8+ T cells elicited from combination CD40/TLR7 treatment demonstrated both lytic activities and interferon (IFN)gamma production and an enhanced secondary response to antigenic challenge. Agonists for TLRs 2/6, 3, 4, and 9 also synergized with CD40 stimulation, demonstrating that synergy with the CD40 pathway is a property of TLR-derived stimuli in general. The CD8+ T cell expansion induced by CD40/TLR7 triggering was independent of CD4+ T cells, IFNgamma, and IL-12 but dependent on B7-mediated costimulation and surprisingly on type I IFN. These studies provide the rational basis for the use of TLR and CD40 agonists together as essential adjuvants to optimize vaccines designed to elicit protective or therapeutic immunity.     

CD_4~+ CD_(25)~+ Foxp3~+调节性T淋巴细胞与Graves病复发的关系

Treg为一群具有免疫抑制效应的T淋巴细胞亚群,在维持机体自身耐受和抑制自身免疫性疾病发生发展中具有重要作用.