SLE患者外周血中Foxp3+CD4+CD25+调节性T细胞的分析

目的分析SLE患者外周血中Foxp3 CD4 CD25 调节性T细胞和T细胞亚群上GITR的表达,以初步阐述其在SLE患者免疫稳态调节中的作用和意义。方法以流式细胞术检测SLE患者外周血中Foxp3 CD4 CD25 调节性T细胞和T细胞亚群上GITR的表达。结果稳定期及活动期SLE患者外周血中Foxp3 CD4 CD25 调节性T细胞比例显著低于健康对照(P<0.05),且活动期SLE患者Foxp3 CD4 CD25 调节性T细胞比例高于稳定期SLE患者(P>0.05)。SLE患者外周血CD3 CD4 T细胞和CD3 CD8 T细胞上GITR表达显著增加(P<0.05);随着疾病活动性增加,CD3 CD4 T细胞上GITR表达降低(P>0.05),CD3 CD8 T细胞上GITR表达增加(P>0.05)。结论SLE患者外周血中Foxp3 CD4 CD25 调节性T细胞表达降低,而患者T细胞亚群上GITR表达增加,其共同作用在诱导SLE患者外周耐受障碍中具有重要意义。     

CD4+ CD25high Treg和CD4+ CD25lowT细胞及PD-1分子在SLE和RA患者外周血中的表达分析

目的:分析SLE和RA患者外周血CD4+CD25highTreg和CD4+CD25low T细胞的数量变化以及两群细胞表面协同刺激分子PD-1分子的表达情况,初步探讨PD-1表达异常在SLE和RA患者细胞免疫失调中的意义.方法:流式细胞术(FCM)检测CD4+CD25highTreg和CD4+CD25lowT细胞的比率以及PD-1的表达率.结果:与健康对照组相比,SLE和RA患者组外周血CD4+CD25highTreg的比率均明显降低(P<0.05);两疾病组间相比,SLE组CD4+CD25highTreg的比率更低(P<0.05).RA患者组CD4+CD25highTreg表面PD-1的表达率明显低于健康对照和SLE组(P<0.05),而SLE组该指标与健康对照无统计学差异(P>0.05).CD4+CD25lowT细胞以及该群细胞上PD-1的表达率在三组间无统计学差异.结论:外周血CD4+CD25highTreg生成不足导致其对效应性T细胞的抑制能力减弱是SLE和RA患者的共同特征;PD-1表达降低可能是RA患者CD4+CD25high曲Treg免疫调节紊乱的重要机制,而在SLE患者PD-1分子并不是影响免疫稳态的主要因素.     

成人麻疹细胞免疫与CD4+ CD25+调节性T细胞的关系

目的 了解CD4+CD25+调节性T细胞(Treg)与麻疹患者细胞免疫的关系.方法 采集34例成年麻疹患者和27例健康对照的外周血,采用流式细胞术进行CD4+CD25+细胞和FoxP3+细胞的检测.用免疫磁珠从外周血单个核细胞(PBMC)分选出CD4+CD25+T细胞和CD4+CD25-T细胞,分别用抗-CD3单克隆抗体、BCG和NV减毒株进行刺激培养,收集培养上清,用ELISA法检测培养上清中的IFN-γ和IL-10.结果 麻疹患者外周血白细胞、淋巴细胞及CD3+CC4·细胞比例明显降低,而CD4+CD25+细胞与FoxP3+细胞的比例则与对照无显著差别;CD4+CD25+细胞明显抑制抗CD3刺激下CD4+CD25-T细胞产生IFN-γ,且患者和对照没有差别,而IL-10的产生没有这种改变.结论 成人麻疹患者的的免疫抑制与Treg的抑制作用无关. 4+CD25+T细胞和CD4+CD25-T细胞,分别用抗-CD3单克隆抗体、BCG和NV减毒株进行刺激培养,收集培养上清,用ELISA法检测培养上清中的IFN-γ和IL-10.结果 麻疹患者外周血白细胞、淋巴细胞及CD3+CC4+细胞比例明显降低,而CD4+CD2 +细胞与FoxP3+细胞的比例则与对照无显著差别;CD4+CD25+细胞明显抑制抗CD3刺激下CD4+CD25-T细胞产生IFN-γ,且患者和对照没有差别,而IL-10的产生     

系统性红斑狼疮患者CD4+T细胞上CD137的表达

目的:探讨系统性红斑狼疮(Systemic lupus erythematosus,SLE)患者CD4 T细胞上共刺激分子CD137的表达及其作用机制。方法:应用流式细胞术检测30例系统性红斑狼疮患者和20例正常对照者外周血T细胞活化前后CD137的表达。结果:活动期SLE患者CD4 T细胞表达的CD137明显高于稳定期及正常对照组(表达百分率分别为21.56±4.08、3.01±0.09和1.24±0.12,P<0.01),稳定期SLE患者表达的CD137与正常对照组比较无统计学差异(P>0.05)。但是活动期和稳定期SLE患者的CD4 T细胞用抗CD3单抗体外刺激活化后表达的CD137均显著高于正常对照组(表达百分率分别为56.25±9.11、27.26±3.41和13.17±1.54,P<0.01)。另外,活动期SLE患者CD4 T细胞活化后表达的CD137与补体呈负相关关系(r=-0.447,P<0.05),与IgG和24小时尿蛋白定量呈正相关关系(r=0.451,P<0.05,r=0.245,P<0.05)。结论:活动期系统性红斑狼疮患者T细胞活化前后CD137的表达均显著增高,而且CD4 T细胞活化后CD137表达水平可能提示病情和肾脏受累程度。     

胃癌患者PBMCs中CD4+CD25+T细胞体外增殖及对CD4+CD25-T细胞增殖的影响

目的:探讨胃癌患者外周血单个核细胞（PBMCs）中的CD4+CD25+T细胞体外增殖及对CD4+CD25-T细胞增殖的影响。 方法:以免疫磁性分离方法 （MACS）分选出胃癌患者外周血单个核细胞中的CD4+CD25+T及CD4+CD25-T细胞后，用流式细胞仪分析细胞的纯度及活力；再以小鼠抗人CD3单抗、小鼠抗人CD28单抗及rh IL-2作为共刺激因子，观察与CD4+CD25-T细胞共培养时，CD4+CD25+T细胞对CD4+CD25-T细胞增殖的抑制效应。 结果:（1）分选后健康对照组及胃癌患者PBMC 中CD4+CD25+ T细胞纯度分别为83.8%±1.84%、84.13%±2.77％，两者相比，无显著差异（P＞0.05）;(2)经MACS 分选后正常对照组与胃癌患者CD4+CD25+ T细胞活力分别为98.52%±0.72%、97.80%±0.95%，两者相比，无显著差异（P＞0.05）；(3)无论是健康对照还是胃癌患者的CD4+CD25+T均具有明显抑制效应性T细胞如CD4+CD25-T细胞的增殖，随着CD4+CD25+T细胞数的增加，这种抑制增殖的能力也相应增加，当CD4+CD25+∶〖KG-*2〗CD4+CD25-T达 1∶〖KG-*2〗1时，抑制率最大达到50％。 结论:MACS分选法能够分选出高纯度及活力的CD4+CD25+T细胞，分选后CD4+CD25+T细胞在体外均能抑制CD4+CD25-T细胞增殖，且这种抑制效应呈一定效靶比关系。     

Caspase-8信号分子对SLE患者T细胞亚群的双向调节作用研究

目的 分析SLE患者外周血T细胞内活化Caspase-8、Caspase-3和T细胞膜上Fas、CD69以及外周血中Foxp3 CD4 CD25 调节性T细胞的表达,探讨他们在SLE患者免疫失衡中的作用.方法 用流式细胞术检测活化Caspase-8、Caspase-3和Fas、CD69以及Foxp3 CD4 CD25 Treg的表达.结果 与健康对照相比,SLE患者外周血CD3 CD4 T细胞上Fas表达显著升高(P＜0.05),无论稳定期或活动期SLE患者CD3 CD4 T细胞和CD3 CD8 T细胞中活化Caspase-8的表达均显著增加(P＜0.05),且稳定期和活动期SLE患者CD3 CD8 T细胞中活化Caspase-8的表达高于其在CD3 CD4 T细胞中的表达(P＜0.05);但是仅活动期SLE患者T细胞内活化Caspase-3表达增加(P＜0.05),同时稳定期和活动期SLE患者CD3 CD4 T细胞中活化Caspase-3的表达高于其在CD3 CD8 T细胞中的表达(P＜0.05).同时SLE患者CD3 CD8 T细胞上CD69表达率升高(P＜0.05),但是CD69在CD3 CD4 T细胞上的表达率与健康对照相比无显著性差异(P＞0.05).SLE患者外周血中Foxp3 CD4 CD25 Treg比例显著低于健康对照(P＜0.05).结论 Caspase-8介导的信号事件同时参与诱导SLE患者淋巴细胞的凋亡与活化,促使SLE患者体内免疫反应向Th2极化,同时由于SLE患者外周血中Foxp3 CD4 CD25 Treg表达降低所介导的免疫抑制效应缺陷,他们共同作用促使SLE患者外周免疫平衡障碍.     

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.     

免疫磁珠法分离人外周血CD4+CD25+调节性T细胞

目的 建立人外周血单个核细胞中CD4 CD25 调节性T细胞(regulatery T cells,Treg)免疫磁性细胞分离力(megnetic activated cell sorting,MACS),并鉴定其分离效率.方法 采用免疫磁珠两步法(即阴性分选和阳性分选2步)分离人周血单个核细胞中的CD4 CD25 调节性T细胞,首先采用生物素标记的鸡尾酒抗体和抗生物素标记的磁珠阴性分选CIM细胞,再用抗CD25 的磁珠阳性分选CD4 CD25 T细胞.分离后的细胞经抗体染色后再通过流式细胞仪检测其分离纯度;内因子染色检测其转录因子FOXV3的表达频率;台盼蓝染色检测细胞的存活率;3H-TdR掺入法检测其对CD4 CD25-T细脆殖抑制效应.结果 阴性分选CD4 T细胞的纯度为(92.2±1.7)%,阳性分选后CD4 CD25 Treg细胞的纯度(95.1±1.2)%.胞内因子染色FOXF3在CD4 CD25 Treg细胞中的表达率为(80.4±1.2)%,台盼蓝染色细胞存活率为(95.6±3.3)%.3H-TdR掺入法检测其对CIM CD25-T细胞具有明显的抑制作用.结论 采用免疫磁性细胞分离技术能够高效、快地得到一群纯度高并且细胞活力好的CD4 CIY25 Treg,为进一步研究其功能提供了方便.     

CD4~+CD25~+调节性T细胞在自身免疫性甲状腺疾病中数量和功能变化

目的:探讨自身免疫性甲状腺疾病患者外周血中CD4+CD25+调节性T细胞(Tregs)的数量和功能变化。方法:采用化学发光法测定20例初发Graves’病人、20例初发桥本甲状腺炎(HT)患者及20例健康体检者血清中促甲状腺素(TSH)、总三碘甲状腺原氨酸(TT3)、总甲状腺素(TT4)、甲状腺球蛋白抗体(TgAb)和甲状腺过氧化酶抗体(TPOAb)的水平;用流式细胞仪分析外周血单个核细胞(PBMC)中CD4+T细胞及CD4+CD25+Tregs的数量;采用磁珠分选技术分选5例HT病人和5例健康体检者PBMC中CD4+CD25+Tregs和CD4+CD25-T细胞,采用MTT法检测CD4+CD25+Tregs对自身CD4+CD25-T细胞增殖的抑制作用;提取各组PBMC的总RNA,经Real time-PCR检测TGFβ-1、Foxp3 mRNA的表达水平。结果:流式细胞检测结果显示,初发Graves’病人、初发HT患者外周血PBMC中CD4+T细胞数量与正常人比较无差异(P<0.05);初发HT患者外周血PBMC中CD4+CD25+Tregs占CD4+T细胞的比率为(1.55%±0.49%),明显低于正常对照组(2.86%±1.04%)(P<0.05);初发Graves’病人外周血PBMC中CD4+CD25+Tregs占CD4+T细胞的比率为(3.25%±0.97%),与正常对照组(2.86%±1.04%)相比无显著性差异(P<0.05)。MTT结果显示,初发HT患者CD4+CD25+Tregs对自身CD4+CD25-T细胞增殖的抑制百分率为15.7%±5.36%,与正常组(41.7%±9.87%)相比显著降低(P<0.05)。Real time-PCR结果显示,初发Graves’病人、初发HT患者PBMC的TGFβ-1 mRNA表达水平分别为(0.37±0.10)和(0.43±0.09),均明显低于正常对照组(1.02±0.04)(P<0.05);初发Graves’病人、初发HT患者PBMC的Foxp3 mRNA表达水平分别为0.62±0.09和0.42±0.29,均明显低于正常对照组(0.99±0.17)(P<0.05)。结论:本研究结果提示,HT患者外周血中CD4+CD25+Tregs的数量和功能明显降低。Graves’病和HT患者外周血PBMC中TGFβ-1、Foxp3 mRNA表达水平明显降低。     

类风湿性关节炎患者CD4+CD25+Foxp3+调节性T细胞检测及意义

目的:研究CD4 CD25 FoxP3 调节性T细胞在类风湿关节炎患者(RA)外周血中的比例改变,并探讨其在疾病进程中的意义.方法:选取活动期及稳定期RA患者,采用细胞内染色的流式细胞术及定量PCR的方法,分别在蛋白质和mRNA水平检测FoxP3表达,并与正常人进行比较.结果:RA患者CD4和CD25双阳性细胞所占比例与对照组没有明显差异,而活动期患者外周血CD4 CD25high和CD4 CD25 FoxP3 细胞明显低于稳定期和对照组(P＜0.05).FoxP3 mRNA表达水平与蛋白质表达水平变化相一致.结论:类风湿性关节炎活动期时CD4 CD25 FoxP3 调节性T细胞明显减少,这群调节性T细胞可能参与了类风湿性关节炎的病理进程.     

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.     

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.     

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.     

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.     

CD4+CD8+ murine intestinal intraepithelial lymphocytes

We have studied a population of CD4+ intestinal intraepithelial lymphocytes using two-color flow cytometric analyses, and in highly purified fluorescent-activated cell-sorted preparations. Although CD4+ T cells present within the epithelial immune compartment comprised only approximately 10-20% of the total intestinal epithelial lymphoid cells, an unusually high proportion of those CD4+ lymphocytes expressed a CD4+CD8+ phenotype which is rarely encountered in peripheral T cells. By comparison, CD4+ lymphocytes from spleen or lymph nodes existed exclusively as single-positive T cells. Analyses of CD4 and CD8 expression on lymphocytes from Peyer's patches, the lamina propria, and IEL indicated that CD4+CD8+ lymphocytes were unique to the IEL. Using CD4+CD8+ preparations obtained by fluorescent-activated cell sorting, CD4+CD8+ epithelial T cells were found also to express CD3 and Thy-1 surface markers. This heretofore undescribed extrathymic population of double-positive T cells constitutes a unique peripheral T cell subset which may be involved in intestinal T cell maturation and development, or could represent a highly specialized effector population.