钙通道与调节性T细胞效应功能的研究进展

调节性T细胞(Treg)为一类具有免疫抑制作用的T细胞,在维持免疫系统正常的外周耐受中发挥了重要作用,其中经典的CD4+CD25+Foxp3+Treg,无论是其数量还是抑制功能异常均可导致自身免疫性疾病。钙离子通道在免疫细胞发挥功能效应中是必不可少的,同样在Treg的发展和效应功能中也起着重要的作用,特别是STIM,ORAI,calcineurin-NFAT通路。现对钙离子通道在Treg的作用作一归纳总结。     

Perspectives on Regulatory T Cell Therapies

Adoptive transfer in animal models clearly indicate an essential role of CD4+ CD25+ FOXP3+ regulatory T (T(reg)) cells in prevention and treatment of autoimmune and graft-versus-host disease. Thus, T(reg) cell therapies and development of drugs that specifically enhance T(reg) cell function and development represent promising tools to establish dominant tolerance. So far, lack of specific markers to differentiate human T(reg) cells from activated CD4+ CD25+ effector T cells, which also express FOXP3 at different levels, hampered such an approach. Recent identification of the orphan receptor glycoprotein-A repetitions predominant (GARP or LRRC32) as T(reg) cell-specific key molecule that dominantly controls FOXP3 via a positive feedback loop opens up new perspectives for molecular and cellular therapies. This brief review focuses on the role of GARP as a safeguard of a complex regulatory network of human T(reg) cells and its implications for regulatory T cell therapies in autoimmunity and graft-versus-host disease.     

微嵌合体、大嵌合体、调节性T细胞与移植免疫耐受

目前,器官移植已成为挽救终末期器官功能衰竭患者生命的惟一有效途径,但移植后长期生存率仍有待提高。慢性排斥反应与长期大量应用免疫抑制剂导致的严重感染及肿瘤性增生是影响移植后长期生存率的主要原因。如何控制移植后的排斥反应和诱发宿主对移植物产生免疫耐受,一直是器官移植领域的热点和难点。移植排异反应与移植耐受的可能机制经典免疫学理论认为,针对异体移植器官的排异反应主要是激活了受体体内的细胞免疫机制。即受体免疫系统识别异体抗原,引起效应T细胞激活和释放一系列效应分子,攻击和排斥异体移植器官。在排异反应中,主要组…     

CD5 Expression Is Developmentally Regulated By T Cell Receptor (TCR) Signals and TCR Avidity

Recent data indicate that the cell surface glycoprotein CD5 functions as a negative regulator of T cell receptor (TCR)-mediated signaling. In this study, we examined the regulation of CD5 surface expression during normal thymocyte ontogeny and in mice with developmental and/or signal transduction defects. The results demonstrate that low level expression of CD5 on CD4⁻CD8⁻ (double negative, DN) thymocytes is independent of TCR gene rearrangement; however, induction of CD5 surface expression on DN thymocytes requires engagement of the pre-TCR and is dependent upon the activity of p56^lck. At the CD4⁺CD8⁺ (double positive, DP) stage, intermediate CD5 levels are maintained by low affinity TCR–major histocompatibility complex (MHC) interactions, and CD5 surface expression is proportional to both the surface level and signaling capacity of the TCR. High-level expression of CD5 on DP and CD4⁺ or CD8⁺ (single positive, SP) thymocytes is induced by engagement of the α/β-TCR by (positively or negatively) selecting ligands. Significantly, CD5 surface expression on mature SP thymocytes and T cells was found to directly parallel the avidity or signaling intensity of the positively selecting TCR–MHC-ligand interaction. Taken together, these observations suggest that the developmental regulation of CD5 in response to TCR signaling and TCR avidity represents a mechanism for fine tuning of the TCR signaling response.     

基于免疫磁珠分选的调节性T细胞亚群嵌合性定量分析

为了探讨免疫分选偶联短串重复序列（STR）方法用于调节性T细胞（Treg）嵌合性定量监测的可行性,以淋巴细胞不同比例混合制备14组人工嵌合体血样,以单个核细胞为起点,以免疫磁珠阴性和阳性选择法获取CD4＋CD25＋Treg细胞,分选后的Treg细胞再进行16位点的STR长度多态性分析。结果显示,从分选后的Treg细胞提取的DNA量能满足STR检测要求,当嵌合体中受体比例≥10%时,16个STR位点均能检出受体和供体特异性等位基因,按照STR峰面积计算的受体比例与理论值相符;当受体比例≤1%时,仅有部分位点能检出受体特异性等位基因,实测嵌合率与理论值存在差异。结论：建立了基于免疫分选的Treg细胞嵌合性定量分析方法,对造血嵌合体的检出灵敏度和准确性在1%-10%,可用于造血干细胞移植术后嵌合体监测。     

Quantitative Impact of Thymic Clonal Deletion on the T Cell Repertoire

Interactions between major histocompatibility complex (MHC) molecules expressed on stromal cells and antigen-specific receptors on T cells shape the repertoire of mature T lymphocytes emerging from the thymus. Some thymocytes with appropriate receptors are stimulated to undergo differentiation to the fully mature state (positive selection), whereas others with strongly autoreactive receptors are triggered to undergo programmed cell death before completing this differentiation process (negative selection). The quantitative impact of negative selection on the potentially available repertoire is currently unknown. To address this issue, we have constructed radiation bone marrow chimeras in which MHC molecules are present on radioresistant thymic epithelial cells (to allow positive selection) but absent from radiosensitive hematopoietic elements responsible for negative selection. In such chimeras, the number of mature thymocytes was increased by twofold as compared with appropriate control chimeras. This increase in steady-state numbers of mature thymocytes was not related to proliferation, increased retention, or recirculation and was accompanied by a similar two- to threefold increase in the de novo rate of generation of mature cells. Taken together, our data indicate that half to two-thirds of the thymocytes able to undergo positive selection die before full maturation due to negative selection.     

免疫治疗联合化疗对多发性骨髓瘤患者外周血T、B淋巴细胞及调节性T细胞水平的影响

【目的】探讨免疫联合化疗对多发性骨髓瘤（MM）患者外周血T、B淋巴细胞及调节性T细胞（Tregs）水平的影响。【方法】本院收治的MM患者60例,采用数字随机对照表分为两组,每组各30例;对照组给予DC-CIK免疫治疗＋化疗,对照组仅给予化疗,评估两组临床疗效,观察两组T淋巴细胞、Tregs水平、B细胞、浆细胞比例水平变化;随访1年,比较两组复发率。【结果】观察组治疗有效率为53．33％（i6／30）显著高于对照组26．67％（8／30）,1年复发率为6．67％（2／30）显著低于对照组30．0％（9／30）,且差异有显著性（P〈0．05）。观察组治疗后CD4＋T淋巴细胞比例、CD4＋／CD8＋T淋巴比值显著高于对照组,CD8＋T淋巴细胞比例显著低于对照组,且差异有显著性（P〈0．05）。观察组治疗后CD4＋CD25＋Tregs、CD4＋CD25 high Tregs显著低于对照组,且差异有显著性（P〈0．05）。观察组治疗后B细胞比例高于对照组,浆细胞比例低于对照组,且差异有显著性（P〈0．05）。【结论】DCcIK免疫治疗＋化疗能够改善MM患者免疫功能紊乱症状,降低浆细胞比例,提高临床疗效。     

Enforced IL-10 Expression Confers Type 1 Regulatory T Cell (Tr1) Phenotype and Function to Human CD4+ T Cells

Type 1 regulatory T (Tr1) cells are an inducible subset of CD4⁺ Tr cells characterized by high levels of interleukin (IL)-10 production and regulatory properties. Several protocols to generate human Tr1 cells have been developed in vitro. However, the resulting population includes a significant fraction of contaminating non-Tr1 cells, representing a major bottleneck for clinical application of Tr1 cell therapy. We generated an homogeneous IL-10–producing Tr1 cell population by transducing human CD4⁺ T cells with a bidirectional lentiviral vector (LV) encoding for human IL-10 and the marker gene, green fluorescent protein (GFP), which are independently coexpressed. The resulting GFP⁺ LV-IL-10–transduced human CD4⁺ T (CD4^LV-IL-10) cells expressed, upon T-cell receptor (TCR) activation, high levels of IL-10 and concomitant low levels of IL-4, and markers associated with IL-10. Moreover, CD4^LV-IL-10 T cells displayed typical Tr1 features: the anergic phenotype, the IL-10, and transforming growth factor (TGF)-β dependent suppression of allogeneic T-cell responses, and the ability to suppress in a cell-to-cell contact independent manner in vitro. CD4^LV-IL-10 T cells were able to control xeno graft-versus-host disease (GvHD), demonstrating their suppressive function in vivo. These results show that constitutive over-expression of IL-10 in human CD4⁺ T cells leads to a stable cell population that recapitulates the phenotype and function of Tr1 cells.     

季德胜蛇药对小鼠树突状细胞功能的影响

目的:观察季德胜蛇药对小鼠树突状细胞(DCs)功能的调节作用.方法:48只BALB-c小鼠随机分为4组,每组各12只,分别为正常对照组、环磷酰胺模型组、治疗1组、治疗2组.各组均以灌胃给药,2次/d,连续21 d,正常对照组和造模组给予同体积的0.9％氯化钠液,治疗组分别给予相应剂量的蛇药治疗.给药第15天起,除正常对照组外各组小鼠均予以环磷酰胺30 mg/kg皮下注射,连续7d制备免疫功能低下模型.比较4组间DCs表型、DCs功能和细胞因子白介素12(IL-12)的浓度.结果:与模型组比较,治疗组小鼠DCs的表面分子主要组织相容性抗原复合物(MHC)-Ⅱ、CD11c的表达水平显著升高、刺激T淋巴细胞增殖的能力以及分泌IL-12均显著增强.结论:季德胜蛇药可提高免疫抑制小鼠树突状细胞的免疫功能.     

调节性T细胞在特发性再生障碍性贫血发病机制中的作用

调节性T细胞（Treg）是一组具有抑制自身免疫反应,阻止免疫损伤病理发生和维持机体免疫平衡作用的T细胞亚群.其特征是持续表达CD25,特异性表达Foxp3,并低表达CD127.Treg可通过细胞接触或者分泌细胞因子对自身反应性T细胞发挥免疫抑制作用,其免疫抑制活性受多种转录因子调控,如Foxp3、T-bet、干扰素调节因子（IRF）-4、GATA结合蛋白-3及信号传导子与转录激活因子（STAT）-3等.近年,对特发性再生障碍性贫血（IAA）的动物模型和IAA患者的研究发现,其存在Treg数量减少,部分研究发现IAA患者存在Treg功能异常.在Foxp3的调控下,Treg对效应T细胞的免疫抑制功能减弱是IAA发病机制之一.笔者拟就Treg的一般特性及其在IAA发病机制中的作用进行综述如下.     

Role of the Multiple T Cell Receptor (TCR)-ζ Chain Signaling Motifs in Selection of the T Cell Repertoire

Immature thymocytes undergo a selection process within the thymus based on their T cell antigen receptor (TCR) specificity that results either in their maturation into functionally competent, self-MHC–restricted T cells (positive selection) or their deletion (negative selection). The outcome of thymocyte selection is thought to be controlled by signals transduced by the TCR that vary in relation to the avidity of the TCR–ligand interaction. The TCR is composed of four distinct signal transducing subunits (CD3-γ, -δ, -ε, and ζ) that contain either one (CD3-γ, -δ, -ε) or three (-ζ) signaling motifs (ITAMs) within their intracytoplasmic domains. A possible function for multiple TCR ITAMs could be to amplify signals generated by the TCR during selection. To determine the importance of the multiple TCR-ζ chain ITAMs in thymocyte selection, transgenes encoding α/βTCRs with known specificity were bred into mice in which ζ chains lacking one or more ITAMs had been genetically substituted for endogenous ζ. A direct relationship was observed between the number of ζ chain ITAMs within the TCR complex and the efficiency of both positive and negative selection. These results reveal a role for multiple TCR ITAMs in thymocyte selection and identify a function for TCR signal amplification in formation of the T cell repertoire.     

Kinetics and Extent of T Cell Activation as Measured with the Calcium Signal

We have characterized the calcium response of a peptide–major histocompatibility complex (MHC)-specific CD4⁺ T lymphocyte line at the single cell level using a variety of ligands, alone and in combination. We are able to distinguish four general patterns of intracellular calcium elevation, with only the most robust correlating with T cell proliferation. Whereas all three antagonist peptides tested reduce the calcium response to an agonist ligand, two give very different calcium release patterns and the third gives none at all, arguing that (a) antagonism does not require calcium release and (b) it involves interactions that are more T cell receptor proximal. We have also measured the time between the first T cell–antigen-presenting cell contact and the onset of the calcium signal. The duration of this delay correlates with the strength of the stimulus, with stronger stimuli giving a more rapid response. The dose dependence of this delay suggests that the rate-limiting step in triggering the calcium response is not the clustering of peptide–MHC complexes on the cell surface but more likely involves the accumulation of some intracellular molecule or complex with a half-life of a few minutes.     

T Cell Receptor (TCR)-β Gene Recombination: Dissociation from Cell Cycle Regulation and Developmental Progression During T Cell Ontogeny

T cell lymphopoiesis involves extensive cell division and differentiation; these must be balanced by export and programmed cell death to maintain thymic homeostasis. Details regarding the nature of these processes, as well as their relationships to each other and to the definitive process of T cell receptor (TCR) gene recombination, are presently emerging. Two widely held concepts are that cell cycle status is inherently and inversely linked to gene recombination and that the outcomes of gene recombination regulate developmental progression. In this study, we analyze TCR-β recombination and cell cycle status with respect to differentiation during early T cell ontogeny. We find that although differentiation, cell cycle fluctuations, and gene recombination are coincident during normal T cell development, differentiation and cell cycle status are not inherently linked to the recombination process or its products. Rather, recombination appears to occur in parallel with these events as part of a genetically patterned program of development. We propose that the outcome of gene recombination (i.e., TCR expression) may not influence developmental progression per se, but instead serves to perpetuate those developing cells that have been successful in recombination. The potential consequences of this model for the regulation of thymic lymphopoiesis and programmed cell death are discussed.     

Stoichiometry of the T cell antigen receptor (TCR) complex: each TCR/CD3 complex contains one TCR alpha, one TCR beta, and two CD3 epsilon chains

The stoichiometry of the subunits that comprise the T cell antigen receptor (TCR) complex is not completely known. In particular, it is uncertain whether TCR alpha and TCR beta proteins are present in the TCR complex as one or multiple heterodimeric pairs. In this study we have used mice transgenic for two different TCR alpha and two different TCR beta proteins to determine the number of TCR alpha and TCR beta chains in a single TCR complex. Individual thymocytes and splenic T cells from double TCR transgenic mice simultaneously expressed all four transgenic TCR proteins on their surfaces. Because the individual TCR alpha and individual TCR beta proteins were biochemically distinguishable, we were able to examine association among the transgenic TCR products. We found that each TCR alpha chain paired with each TCR beta chain, but that each TCR complex contained only one TCR alpha and one TCR beta protein. Furthermore, quantitative immunofluorescence revealed that T cells expressed twice as many CD3 epsilon as TCR beta proteins. These findings demonstrate that there are precisely one TCR alpha, one TCR beta, and two CD3 epsilon chains in each TCR/CD3 complex expressed on the surfaces of both thymocytes and mature T cells.     

自体调节性T细胞可抑制恶性淋巴瘤细胞的增殖

本研究探讨自体调节性T细胞对T细胞淋巴瘤细胞系EIA的作用及其机制。应用免疫磁珠分离法（MACS）分选获得C57BL／6小鼠CD4＋CD25＋T细胞（Treg细胞）,流式细胞术检测细胞纯度及Foxp3表达情况,MTY比色法检测分选的Treg细胞对T细胞淋巴瘤细胞系EL4的体外抑制作用,应用ELISA方法检测TGF—B1和IL-10的含量。结果表明：MACS分选获得CIM＋CD25＋T细胞纯度达91．6％,活细胞比例〉95％,Foxp3表达率为78．9％。MTT比色法证实自体Treg细胞在体外能够明显抑制EIA细胞的增殖（P〈0．05）,且呈细胞因子非依赖性。作者首次证明,自体Treg细胞体外有明显抑制T细胞淋巴瘤细胞系EIA增殖的作用。     

B Cell Differentiation and Immunoregulatory T Cell Function in Human Cord Blood Lymphocytes

The functional maturity of T and B lymphocyte populations from human newborns was evaluated using a reverse hemolytic plaque assay to detect immunoglobulin-secreting cells generated in in vitro cultures stimulated with pokeweed mitogen (PWM), a T cell-dependent polyclonal activator, and the Epstein-Barr virus (EBV), a T cell-independent B cell activator. Cord blood lymphocytes failed to produce immunoglobulin in response to PWM, but did respond with immunoglobulin synthesis to stimulation with EBV. Co-culture experiments demonstrated that cord blood T cells would inhibit immunoglobulin production by adult cells stimulated with PWM, but not with EBV. Cord blood T cells did suppress immunoglobulin production by cord blood B cells when stimulated with a mixture of EBV and PWM, indicating that cord blood, in contrast to adult blood, contains a population of suppressor T cell precursors that are easily activated by PWM. Irradiation of the cord blood T cells with 2,000 rad eliminated the suppressor activity and revealed normal helper function for immunoglobulin (Ig) G, A, and M when these T cells were co-cultured with adult B cells. Cord blood B cells co-cultured with adult T cells or irradiated cord blood T cells did produce immunoglobulin in response to PWM, but the response was significantly lower than that of adult B cells, and only IgM was produced in these cultures. These studies demonstrate that both the T and B cells of the human newborn have significant functional differences compared with the functions of T and B lymphocyte populations in adults.     

天然调节性T细胞的调节因素研究进展

天然CD4^＋CD25^＋调节T细胞来源于胸腺,通过直接接触机制抑制效应细胞的增殖,调节自身免疫和移植免疫。本文主要综述了影响天然调节T细胞分化、发育和功能的主要因素和可能机制。Foxp3是Treg的标志,检测其表达可以作为判定Treg的方法。IL-2主要通过IL-2Rα及STAT5途径促进Treg的增殖活化。膜型和分泌型TGF-β具有不同功能,膜型TGF-β1可能主要介导Treg的抑制功能,而分泌型TGF-β可能主要促进Treg的增殖。树突状细胞由于作用途径不同,对Treg既有正调节,也有负调节。CTLA-4途径可能通过作用于Treg自身、DC或效应细胞直接或间接地调节Treg的功能。     

抗T淋巴细胞单克隆抗体对再生障碍性贫血患者细胞免疫功能的调节作用

为了探讨再生障碍性贫血(AA)的免疫发病机制及抗T淋巴细胞单克隆抗体(MdAb-T)的免疫调节治疗作用,采用酶联免疫法和放射免疫法,检测30例AA患者McAb-T治疗前后周围血T淋巴细胞亚群,血清肿瘤坏死因子α(TNF-α)和白细胞介素2(IL-2)水平及其中10例AA外周血单个核细胞(PBMNC)体外诱生TNF-α和IL-2水平的变化。结果表明:治疗前AA患者T淋巴细胞亚群CD4/CD8比值降低或倒置(P<0.001);淋巴细胞HLA-DR抗原表达增高(P<0.001);血清TNF-α水平显著增高(P<0.01);PBMNC诱生的TNF-α和IL-2水平均明显高于正常对照(P<0.01)。治疗后T淋巴细胞亚群比例恢复正常,血清TNF-α和PBMNC诱生的TNF-α和IL-2水平降低,与对照组比较无显著差异(P>0.05)。T淋巴细胞亚群比例失调和TNF-α与IL-2等造血调控因子异常分泌在AA发病机制中起重要作用。McAb-T能发挥特异性的免疫调节作用,解除T淋巴细胞及相关细胞因子对造血功能的直接或间接抑制作用。     

Distinct Effects of IL-18 on the Engraftment and Function of Human Effector CD8+ T Cells and Regulatory T Cells

IL-18 has pleotropic effects on the activation of T cells during antigen presentation. We investigated the effects of human IL-18 on the engraftment and function of human T cell subsets in xenograft mouse models. IL-18 enhanced the engraftment of human CD8⁺ effector T cells and promoted the development of xenogeneic graft versus host disease (GVHD). In marked contrast, IL-18 had reciprocal effects on the engraftment of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) in the xenografted mice. Adoptive transfer experiments indicated that IL-18 prevented the suppressive effects of Tregs on the development of xenogeneic GVHD. The IL-18 results were robust as they were observed in two different mouse strains. In addition, the effects of IL-18 were systemic as IL-18 promoted engraftment and persistence of human effector T cells and decreased Tregs in peripheral blood, peritoneal cavity, spleen and liver. In vitro experiments indicated that the expression of the IL-18Rα was induced on both CD4 and CD8 effector T cells and Tregs, and that the duration of expression was less sustained on Tregs. These preclinical data suggest that human IL-18 may have use as an adjuvant for immune reconstitution after cytotoxic therapies, and to augment adoptive immunotherapy, donor leukocyte infusions, and vaccine strategies.