特发性血小板减少性紫癜患者CD4~+ CD25~+ Treg细胞和TGF-β1的相关研究

目的:研究特发性血小板减少性紫癜(ITP)患者外周血CD4+ CD25+调节性T细胞(Treg)及相关细胞因子转化生长因子β1(TGF-β1)的表达水平,探讨二者在ITP发病机制中的作用。方法:流式细胞术(FCM)检测31例ITP患者及25例健康志愿者外周血Treg细胞的数量,ELISA方法检测血清中TGF-β1的含量,并进行相关性分析。结果:ITP患者外周血CD4+ CD25+调节性T细胞数量显著低于正常对照组(P0.05),血清TGF-β1的含量也较正常对照组明显减低(P0.05),差异有统计学意义。但CD4+ CD25+调节性T细胞比例与TGF-β1的含量无相关性(P0.05)。结论:ITP患者CD4+ CD25+调节T细胞数量减少与ITP的细胞免疫失调有关,CD4+ CD25+调节性T细胞和TGF-β1在ITP中作用机制复杂,还需要进一步研究。     

Graves病患者131I治疗前后CD4+CD25+ Foxp3+调节性T细胞的变化

目的:通过对Graves病患者131I治疗前后外周血各淋巴细胞亚群和CD4+CD25+ Foxp3+调节性T细胞含量以及相关基因Foxp3mRNA表达水平的测定,探讨131I治疗方法是否可以通过改变调节性T细胞的含量从而改善Graves病患者的免疫功能异常。方法:采集30例Graves病患者131I治疗前及治疗后1个月的外周血,流式细胞仪检测外周血CD3+、CD3+CD4+、CD3+CD8+、CD3-CD19+、CD3-CD16+CD56+淋巴细胞亚群及CD4+CD25+ Foxp3+调节性T细胞的百分率,Real-TimePCR检测外周血单个核细胞Foxp3mRNA的表达水平。结果:和治疗前相比,Graves病患者131I治疗1个月后外周血CD3+CD4+T细胞和CD3-CD19+B细胞百分率都明显减少(P<0.05),CD3-CD16+CD56+NK细胞百分率明显增加(P<0.05),CD3-CD8+T细胞、CD4+CD25+ Foxp3+调节性T细胞百分率和Foxp3mRNA的表达水平无明显变化。结论:131I不能通过增加调节性T细胞的含量而改善Graves病患者的免疫耐受障碍,但可以通过减少CD4+T和B淋巴细胞的含量和增加NK细胞的含量来控制过度的免疫应答。     

结核性胸膜炎患者外周血及胸水中CD4~+ CD25~+ CD127~-调节性T细胞表达水平的临床意义

目的:探讨结核性胸膜炎外周血和胸水中CD4+ CD25+ CD127-调节性T细胞表达水平及其临床意义。方法:收集住院收治的初治结核性胸膜炎患者30例和非结核性胸膜炎患者20例,另选择健康体检人员20例为正常对照组。流式细胞术检测外周血及胸水中CD4+ CD25+ CD127-调节性T细胞的百分率。结果:结核性胸膜炎组外周血中CD4+ CD25+ CD127- Treg细胞占CD4+T细胞总数的百分比显著高于正常对照组和非结核性胸膜炎组(P<0.05)。结核性胸膜炎组胸水中CD4+ CD25+ CD127- Treg细胞占CD4+T细胞总数的百分比明显高于非结核性胸膜炎组(P<0.05)。结核性胸膜炎组患者在规则治疗1、3、7、14 d时,外周血和胸水中CD4+ CD25+ CD127- Treg细胞占CD4+T细胞总数的百分比均逐渐下降,外周血中CD4+ CD25+ CD127- Treg细胞占CD4+ T细胞总数的百分比于治疗3 d时显著低于入院时水平(P<0.05),胸水中CD4+ CD25+ CD127- Treg细胞占CD4+ T细胞总数的百分比于治疗7 d时显著低于入院时水平(P<0.05)。结论:CD4+ CD25+ CD127-调节性T细胞参与了结核性胸膜炎的发病机制,且可作为判断肺结核患者的免疫状态、指导用药、疗效观察的指标。     

浆细胞性乳腺炎患者外周血CD4+CD25+CD127-调节性T细胞变化

目的:观察浆细胞性乳腺炎(Plasma cell mastitis,PCM)患者外周血CD4+ CD25+ CD127-调节性T细胞(CD4+CD25+ CD127-Treg)数量和功能变化,以探讨PCM免疫病理机制.方法:将58例浆细胞乳腺炎患者分成三组:其中急性组13例(22％)、亚急性组25例(43％)和慢性组20例(34％).并设正常对照组20例及乳腺癌对照组16例.以流式细胞术检测各型PCM患者外周血中CD4 +CD25+ CD127 Treg细胞百分率;实时荧光定量RT-PCR检测转录因子Foxp3表达及ELISA检测TGF-β水平.结果:三组PCM组与正常组相比,外周血CD4+ CD25+ CD127 Treg数量,外周血PBMC中Foxp3表达及血浆TGF-β水平均下降(P＜0.05),其中急性PCM组下降最为明显(P＜0.01),乳腺癌组三项指标均升高(P＜0.05).结论:浆细胞性乳腺炎患者的CD4+ CD25+ CD127-Treg数量及功能有所下降.     

卵巢癌患者外周血CD4+CD25hiCD127lo调节性T细胞格局变化及临床意义

目的:观察卵巢癌患者外周血中CD4+CD25hiCD127lo调节性T细胞格局变化及其相关免疫细胞因子TGF-β1、IL-10的变化及与临床病理特征之间的关系,探讨其临床意义.方法:采用流式细胞术(FCM)和酶联免疫吸附法(ELISA)检测70例卵巢癌患者、50例卵巢良性疾患及70例健康者外周血单个细胞中调节性T细胞的比率和血浆TGF-β1、IL-10的水平.结果:①卵巢癌患者外周血中CD4+CD25hiCD127loTreg调节性T细胞占CD4+细胞的比例为6.32%±1.46%(n=70),显著高于卵巢良性疾患4.03%±1.25%(n=50)和健康对照组3.21%±0.96%(n=70),均P＜0.01.术后患者CD4+CD25hiCD127loTreg比率与术前比较无明显差异.②卵巢癌患者血浆中TGF-β1、IL-10水平(256.68±56.34) pg /ml、(28.24±3.12) ng/ml,明显高于良性疾患(156.48±43.68) pg /ml、(20.58±2.39) ng/ml与健康对照组(130.24±35.60) pg/ml、(18.38±2.98) ng/ml,有统计学差异,分别P＜0.001,P＜0.01.③术前卵巢癌患者外周血CD4+CD25hiCD127loTreg比率、血浆中TGF-β1、IL-10水平与患者的临床分期、淋巴结转移以及远处转移有关,P＜0.05～P＜0.001.④相关分析显示,卵巢癌患者外周血 CD4+CD25hiCD127loTreg比率与血浆中TGF-β1水平、IL-10水平呈正相关,r=0.734,P＜0.01;r=0.665,P＜0.01.结论:①CD4+CD25hiCD127loTreg在卵巢癌患者外周血中表达显著增高,这可能是卵巢癌患者免疫功能下降的一个重要原因,并与临床病理特征存在显著相关性;②卵巢癌患者血浆中抑制性细胞因子TGF-β1、IL-10水平明显升高,并与临床病理特征存在显著相关性;③CD4+CD25hiCD127loTreg与TGF-β1、IL-10水平存在正相关,CD4+CD25hiCD127loTreg可能通过产生抑制性细胞因子TGF-β1、IL-10 对效应性T细胞发挥抑制作用.     

颅内动脉粥样硬化性脑梗死患者外周血CD4+CD25+FOXP3+调节性T细胞检测及意义

目的探讨颅内动脉粥样硬化性脑梗死患者外周血CD4+CD25+FOXP3+调节性T细胞(Treg细胞)的变化及意义。方法入选50例颅内动脉粥样硬化性脑梗死患者,同时以正常人群(30例)为对照。用流式细胞分析法测定外周血中CD4+CD25+FOXP3+占CD4+细胞的比例,定量PCR检测转录因子FOXP3的mRNA水平,ELISA检测外周血血浆Treg相关细胞因子IL-10、IL-6和TGF-β的表达。结果颅内动脉粥样硬化性脑梗死患者外周血Treg/CD4+T细胞比例和FOXP3的mRNA水平显著低于正常人群组。颅内动脉粥样硬化性脑梗死患者的IL-10和TGF-β水平低于正常人群组,IL-6水平高于正常人群组。结论颅内动脉粥样硬化性脑梗死患者外周血Treg比例减少,对炎症反应的抑制作用减弱,由此可以推测Treg细胞参与了颅内动脉粥样硬化性脑梗死的发生发展。     

强直性脊柱炎患者外周血CD4+调节性T细胞的变化及意义

目的 探讨强直性脊柱炎(ankylosing spondylitis,AS)患者外周血中CD4+调节性T细胞(regulatory T cells,Treg)的表达、功能及意义.方法 采用流式细胞术检测78例AS患者和50例健康志愿者外周血中CD4+CD25+CD127lo/- Treg、细胞毒性T细胞(cytotoxic T lymphocytes,CTL)和NK细胞,采用ELISA法检测血清中β型转化生长因子(transforming growth factor-β,TGF-β)和肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)的表达水平.从患者外周血单个核细胞中磁珠分选出CD4+CD25+ Treg细胞,混合淋巴细胞培养(mixed lymphocyte culture, MLC)分析其免疫抑制功能.结果 AS活动期患者外周血中CD4+CD25+CD127lo/-Treg占CD4+ T淋巴细胞的百分比为(4.36±1.21)%,MLC中CD4+CD25+ Treg抑制同种异体T淋巴细胞增殖功能低下,与其Treg分泌TGF-β减少相关,CD4+ Treg含量及功能均低于健康志愿者(P<0.05).AS患者外周血中CD4+CD25+CD127lo/- Treg水平与TGF-β呈正相关,与TNF-α呈负相关.结论 AS患者外周血中Treg表达水平低,且存在功能缺陷,导致体内诱导免疫耐受机能不足,可能参与AS免疫发病.     

风湿性心脏病患者的CD4~+CD25~+调节性T细胞及细胞因子的改变及意义

目的:探讨相较于正常人,风湿性心脏病(RHD)患者的血液细胞因子及CD4+CD25+调节性T细胞的改变及意义。方法:分析2012年4月至2013年7月在我院接受住院治疗的RHD患者(观察组)的临床资料,对照组是从我院体检中心选取的健康体检人员,对两组研究对象外周血标本中的转化生长因子-β1(TGF-β1)、肿瘤坏死因子-α(TNF-α)、白细胞介素10(IL-10)、白细胞介素6(IL-6)及CD4+CD25+调节性T细胞表达水平进行检测和比较。结果:本研究共纳入受试者76例,其中观察组患者40例,对照组36例。观察组患者的CD4+CD25+T占淋巴细胞比例(t=17.37,P0.01)、CD4+CD25+Foxp3+Treg占CD4+T比例(t=9.224,P0.01)均显著低于对照组;观察组患者的TGF-β1(t=9.036,P0.01)、IL-10(t=12.11,P0.01)均显著低于对照组,而TNF-α(t=2.331,P=0.013)、IL-6(t=2.239,P0.01)水平则高于对照组,差异均有统计学意义。结论:RHD患者CD4+CD25+调节性T细胞水平明显降低,血液细胞因子如TGF-β1和IL-10也相应地出现下降。     

HIV感染者外周血CD4+ CD25+ Foxp3+/CD127low/-调节性T细胞表达水平对疾病进展的影响

目的:探讨HIV感染者外周血中CD4+ CD25+Foxp3+调节性T细胞(Treg)、CD4+ CD25+ CD127low/-Treg的水平及其与其他免疫指标的关系.方法:采集68例未经抗HIV治疗的HIV/AIDS患者(长期不进展组即LTNP组29例、典型进展的HIV感染组27例、AIDS组12例)及20例健康成人的外周抗凝全血,经免疫荧光染色,应用流式细胞仪分析CD4+T细胞、CD8+T细胞、NK细胞及CD4+CD25+Foxp3+/CD127low/-Treg的含量,并进行统计学分析.结果:除CD8+T细胞外,HIV/AIDS患者外周血中CD4+T细胞、NK细胞、CD4 +/CD8+结果均明显低于健康对照组(P＜0.05);随着疾病的进展,LTNP组、HIV组、AIDS组CD4+T细胞百分比、绝对值计数,CD8+T细胞绝对计数,NK细胞绝对计数,CD4 +/CD8+比值逐渐下降,而CD8+T细胞百分比逐渐上升.对CD4+ CD25+ Foxp3+ Treg与CD4+ CD25+CD127low/-Treg百分含量、绝对计数进行多重比较发现,各组间CD4+ CD25+ Foxp3+ Treg与CD4-CD25+ CD127low/-Treg所占CD4+T细胞百分含量的差异均有统计学意义(P＜0.05),并且随着疾病的发展,CD4+ CD25+ Foxp3+/CD127low/ Treg细胞百分含量逐渐上升,LTNP组与健康对照组之间、HIV组和AIDS组之间CD4+ CD25+Foxp3+/CD127low/ Treg绝对计数差异无统计学意义(P＞0.05),其余各组间的差异均有统计学意义(P＜0.05),并且随着疾病的发展,CD4+ CD25+ Foxp3-/CD127low/-Treg绝对计数逐渐下降.结论:CD4+ CD25+ Foxp3 +/CD127low/-Treg在HIV持续感染的免疫发病机制中有一定作用.     

多发性骨髓瘤患者外周血Th1/Th2及CD4~+CD25~+Tregs的表达分析

目的:检测多发性骨髓瘤(MM)患者外周血T辅助细胞亚群(Th1/Th2)及调节性T细胞(CD4+CD25+Tregs)数量和比例的变化,探讨其T细胞免疫功能状态及临床意义。方法:流式细胞术(FCM)检测31例MM患者及20例健康志愿者外周静脉血Th1/Th2及CD4+CD25+Tregs的比例并分析比较。结果:(1)II、III期MM患者Th1细胞比例较对照组降低,III期Th2细胞比例较对照组及I期降低,差异具有显著性;II、III期MM患者CD4+CD25+、CD4+CD25high、CD4+CD25highCD127low细胞比例均高于正常组,III期CD4+CD25high、CD4+CD25highCD127low较I期增高,差异具有显著性。(2)化疗后复发组MM患者Th1细胞比例较对照组降低,初诊组及化疗后复发组Th2细胞比例较对照组及稳定期组降低,差异具有显著性;初诊组及化疗后复发组CD4+CD25+、CD4+CD25high、CD4+CD25highCD127low细胞比例均高于正常组,复发组CD4+CD25+、CD4+CD25high、CD4+CD25highCD127low明显高于稳定组及初诊组,差异具有显著性。(3)相关性分析Th1、Th2细胞与CD4+CD25+Tregs存在不同程度的负相关(均P0.05或0.01)。结论:MM患者外周血Th1、Th2细胞比例降低,调节性T细胞比例增高,两者相互调节,并与疾病临床分期、病情进展相关,对指导治疗也有一定的价值。     

Lower proportion of CD19+IL-10+ and CD19+CD24+CD27+ but not CD1d+CD5+CD19+CD24+CD27+ IL-10+ B cells in children with autoimmune thyroid diseases

Abstract

Introduction: As it is generally known, regulatory B cells (Bregs) control inflammation and autoimmunity. The significance of Bregs in the population of children with autoimmune thyroid diseases (AITD) still offers plenty of potential to explore. The aim of this study was to estimate the expression of Bregs (phenotype CD19⁺CD24⁺CD27⁺IL-10⁺, CD19⁺IL-10⁺, CD1d⁺CD5⁺CD19⁺IL-10⁺ and CD1d⁺CD5⁺CD19⁺CD24⁺CD27⁺) in a paediatric cohort with AITD and in health controls.

Materials and methods: A total of 100 blood samples were obtained from 53 paediatric patients with Graves’ disease (GD) (N?=?12 newly diagnosed, mean age 12.5?±?3.5 and N?=?17 during methimazole therapy, mean age 12.7?±?4.4), Hashimoto’s thyroiditis (HT) (N?=?10 newly diagnosed, mean age 13.3?±?2.9 and N?=?10 during L-thyroxine therapy, mean age 13.7?±?3.4) and compared with healthy controls (C) (N?=?15, mean age 13.1?±?3.1). The expressions of the immune cell populations were analysed by four-color flow cytometry using a FASC Canto II cytometer (BD Biosciences).

Results: There was a decreasing tendency in the number of lymphocytes B producing IL-10 (B10) cells among all B lymphocytes and more widely, also among all lymphocytes, in each study group, as compared to C. We reported a reduction in IL-10 production in Bregs with the expression of CD19⁺CD24⁺CD27⁺IL-10 and CD1d⁺CD5⁺CD19⁺IL-10⁺ in both untreated and treated AITD.

Conclusions: Our data demonstrate that the reduction in the number of Bregs with CD19⁺CD24⁺CD27⁺IL-10⁺ and CD19⁺IL-10⁺ expression could be responsible for breaking immune tolerance and for AITD development in children.     

Circulating CD3+ CD4+ CD+ T lymphocytes in multiple sclerosis

Triple-antibody flow cytometry was used to search for distinctive populations of peripheral blood lymphocyte immunophenotypes in multiple sclerosis (MS). Using monoclonal antibodies to the cell surface markers CD3, CD4, and CD8, T cell subsets were quantified on a cohort of 31 MS patients (not treated with corticosteroids for at least 6 months), 30 healthy donors, and 14 patients with other autoimmune diseases (also corticosteroid treatment-free for at least 6 months). Untreated MS patients displayed a significantly greater population of CD3+CD4+CD8+ circulating T cells than healthy donors (P = 0.023). Patients with other autoimmune diseases displayed mean populations of CD3+CD4+CD8+ cells greater than normal donors and less than MS, but not significantly different from either. An additional 45 MS patients who had received corticosteroid therapy within the previous 6 months were phenotyped. Treatment of symptomatic MS with corticosteroids was associated with a smaller population of circulating CD3+CD4+CD8+ cells. Some MS patients have significantly greater numbers of peripheral blood T lymphocytes simultaneously expressing CD3, CD4, and CD8 surface markers than healthy donors and this population of cells may be reduced by corticosteroids treatment. This triple positive phenotype may be a manifestation of a systemic immune abnormality in MS.     

Expansion and differentiation of CD14+CD16(-) and CD14+ +CD16+ human monocyte subsets from cord blood CD34+ hematopoietic progenitors

To determine whether monocytes can be generated from CD34+ hematopoietic progenitors in large numbers, cord blood CD34+ cells were first expanded for 3-10 days in X-VIVO 10 medium supplemented with FCS, stem cell factor (SCF), thrombopoietin (TPO), and Flt-3 Ligand (Flt-3L), and then differentiated in IMDM medium supplemented with FCS, SCF, Flt-3L, IL-3 and M-CSF for 7-14 days. These two step cultures resulted in up to a 600-fold mean increase of total CD14+ cells. Using this approach, two subpopulations of monocytes were obtained: CD14+CD16(-) and CD14++CD16+ occurring at 2:1 ratio. 1.25(OH)2 Vitamin D3 added to the differentiation medium altered this ratio by decreasing proportion of CD14++CD16+ monocytes. In comparison to CD14+CD16(-), the CD14++CD16+ cells showed different morphology and an enhanced expression of CD11b, CD33, CD40, CD64, CD86, CD163, HLA-DR, and CCR5. Both subpopulations secreted TNF and IL-12p40 but little or no IL-10. CD14++CD16+ monocytes released significantly more IL-12p40, were better stimulators of MLR but showed less S. aureus phagocytosis. These subpopulations are clearly different from those present in the blood and may be novel monocyte subsets that represent different stages in monocyte differentiation with distinct biological function.     

Human CD4+CD25+ regulatory T cells

In this report, we review studies of human CD4+CD25+ regulatory T cells (T-reg). Although lagging a few years behind the discovery of these cells in the mouse, the equivalent population of CD4+CD25+ regulatory T cells has also been isolated from human peripheral blood, thymus, lymph nodes and cord blood. In general, the characteristics of this T cell subset are strikingly similar between mouse and man. In the recent explosion of research reports on human CD4+CD25+ cells, although the majority of the characteristics ascribed to these cells appear to be consistent, contrasting results have been found primarily in regards to potential involvement of TGFbeta and production of IL-10. One explanation for this variability may reside in the fact that markedly different techniques are used to isolate human CD4+CD25+ T-reg cells and thus may result in the comparison of T-reg populations that differ in cellular composition and/or activation state. Another potential explanation for differences in human T-reg function may rest on the extreme variability of the culture conditions and TCR stimuli that have been used to test the functional properties of these cells in vitro. The strength of the TCR signal provided to the culture greatly affects the functional outcome of the co-culture and can result in the difference between suppression and full activation. Surprisingly, it appears that stronger stimulation has a greater and more rapid effect on the T-resp cell than on the T-reg cell as it causes T-resp cells to quickly become resistant to suppression. Thus, the details of in vitro culture conditions may at least partially account for disparate findings in regard to the functional characterization of human CD4+CD25+ cells. Here we review the evidence regarding the identification of human CD4+CD25+ regulatory T cells and their possible mechanism(s) of function.     

Circulating CD4+CD25+ and CD4+CD25+ T cells in myasthenia gravis and in relation to thymectomy

Studies in experimental animal models of human autoimmune diseases have revealed that CD4⁺CD25⁺ T regulatory (Tr) cells are of thymic origin and have potentials in preventing auto‐aggressive immunity. Myasthenia gravis (MG) is the best‐characterized autoimmune disease. Changes in the thymus are found in a majority of patients with MG. Thymectomy has beneficial effects on the disease severity and course in a substantial proportion of MG patients. But the occurrence and characteristics of Tr cells have not yet been defined in MG. We determined the frequencies and properties of circulating CD4⁺CD25⁺ versus CD4⁺CD25^– cells in MG patients and healthy controls (HCs), with special focus on the effect of thymectomy on CD4⁺CD25⁺ cells. CD4⁺CD25^high cells comprise only about 2% of blood lymphocytes in both MG patients and HCs. Frequencies of CD4⁺CD25^high cells were similar in MG patients irrespective of treatment with thymectomy. CD4⁺CD25⁺ cells in both MG patients and HCs are mainly memory T cells and are activated to a greater extent than CD4⁺CD25^– cells, as reflected by high levels of CD45RO and human leucocyte antigen (HLA)‐DR‐positive cells. In both MG patients and HCs, CD4⁺CD25⁺ cells also contained a high proportion of CD95‐expressing cells as possible evidence of apoptosis‐proneness. Upon stimulation with anti‐CD3/CD28 monoclonal antibodies, CD4⁺CD25⁺ cells responded more vigorously than CD4⁺CD25^– cells in MG, irrespective of treatment with thymectomy, as well as in HCs. Although CD4⁺CD25^– cells are mainly naïve T cells, in non‐thymectomized MG patients, they are activated to a greater extent as reflected by higher expression of HLA‐DR and CD95 on the surface compared to HCs. The data thus show that there is no deficiency of CD4⁺CD25⁺ cells in MG, nor is the proportion of CD4⁺CD25⁺ cells influenced by thymectomy.     

Prognostic Values of CD38+CD101+PD1+CD8+ T Cells in Pancreatic Cancer

Programmed death-1 (PD-1), a key immune checkpoint molecule, has been developed as an oncotherapy target for various carcinomas. However, treatment with anti-PD-1 elicited only a minimal effect in pancreatic ductal adenocarcinoma (PDAC). Subsequent studies revealed the existence of a subset of PD-1⁺ T cells coexpressing CD38 and CD101, representing a fixed dysfunctional subpopulation that are not able to be rescued by anti-PD-1 immunotherapy. However, whether this subpopulation of PD-1 expressing CD8⁺ T cells could be useful in predicting PDAC stage or prognosing survival is unknown. In this study, we used flow cytometry and immunofluorescence assay to analyze the expression of CD38 and CD101 in 183 clinical PDAC samples, including 84 of peripheral blood and 99 of surgical tissues. High coexpression of CD38/CD101 on peripheral PD-1⁺CD8⁺ T cells or tumor-infiltrating lymphocytes (TILs) was found to be most significantly correlated with Tumor/Node/Metastasis (T/N/M) classification and clinical stage, in contrast PD-1⁺CD8⁺ T cells could not correlate with T classification. CD38/CD101 co-repression on TILs also correlated with the poor survival in these PDAC patient samples. Our data suggest that CD38/CD101 might represent a more helpful biomarker than PD-1 alone for diagnosis and prognosis of PDAC.     

CD4+ CD45RA+ and CD4+ CD45RO+ T cells differ in their TCR-associated signaling responses.

Peripheral CD4+ T cells can be divided into two different functional populations based on the expression of distinct isoforms of the surface molecule CD45. We have investigated the differences in the proximal signaling induced by anti-CD3 monoclonal antibody in purified populations of "naive" CD45RA+ and "memory" CD45RO+ human CD4+ T cells. Expression of cell surface CD3, CD4 and CD28 was comparable between RA+ and RO+ cells. However, TCR-directed stimulation in the form of anti-CD3 produced markedly different patterns of intracellular signaling. Greater inositol triphosphate generation occurred in naive cells and the rise in intracellular free calcium was also substantially greater in naive than in memory cells. Cells with the naive phenotype were considerably more active in TCR-dependent tyrosine phosphorylation, both at an overall level and specifically in terms of TCR-zeta and ZAP-70 phosphorylation. Despite these differences in phosphorylation, the amounts of TCR-zeta, ZAP-70 and Ick were equivalent between the two subsets. These findings suggest that the TCR-dependent signaling is differentially regulated in naive and memory CD4+ T cells. This may be due to differences in the way that the two isoforms of the CD45 phosphatase regulate the activity of proximal kinases in the TCR signaling pathway, and could be an important means by which the unique functions of differentiated T cell populations are maintained.     

Alloantigen-induced regulatory CD8+CD103+ T cells

Regulatory T cells (Tregs) appear of great importance in the balance between alloreactivity and tolerance and subsets of both CD4(+) and CD8(+) T cells have been recognized to function as regulatory T cells after allogenic transplantation. Among the CD8(+) T-cell subsets, the CD103(+) cells were most recently identified as regulatory. In this review, we describe their phenotypical and functional properties, as well as their relevance for the alloimmune response in vivo. These CD8(+)CD103(+) Tregs are generated within mixed lymphocyte cultures (MLCs) and are elevated by additional transforming growth factor-beta. Interestingly, myeloid dendritic cells are the responsible cell type for induction of CD103(+) Tregs. Allostimulated CD8(+)CD103(+) Tregs display an antigen-experienced effector phenotype with limited effector functions such as cytotoxicity and interferon-gamma production and show a reduced proliferation capacity after restimulation. Beside this anergic phenotype, CD8(+)CD103(+) Tregs are able to suppress alloreactive effector T cells. Through intracellular cytokine staining and transwell assays, we showed that the mechanism of suppression is cytokine independent, but close cell-cell contact is required for suppression.     

CD25+CD4+ regulatory T-cells in cancer

Regulatory T-cells (T_reg) protect the host from autoimmune disease by suppressing self-reactive immune cells. As such, T_reg may also block antitumor immune responses. Recent observations by us and others showed that the prevalence of T_reg is increased in cancer patients, particularly in the tumor environment. Our studies in a mouse pancreas cancer model suggest that the tumor actively promotes the accural of T_reg through several mechanisms involving activation of naturally occurring T_reg as well as conversion of non-T_reg into T_reg. Our studies focus on further defining these mechanisms with the ultimate goal of designing strategies that block T_reg-mediated suppression in cancer patients.