重症肌无力患者外周血中CD4~+CD25~+调节性T细胞的变化及意义

研究CD4 + CD2 5 + 调节性T细胞在重症肌无力 (MG )发病中的作用。本文采用三色流式细胞术对 2 9例MG患者和 2 3例健康对照者外周血中CD4 + CD2 5 + T细胞 (CD3+ CD4 + CD2 5 + )的百分率进行测定。结果显示病情未能很好控制的MG患者外周血CD4 + CD2 5 + T细胞比率略低于健康对照组 (分别为 3 79%± 1 4 0 %、 4 5 3%± 0 96 % ,P =0 12 ) ,病情稳定或缓解的MG患者CD4 + CD2 5 + T细胞比率 (8 4 5 %± 1 96 % )显著高于健康对照组 (P =0 0 0 0 1) ;胸腺切除的MG患者CD4 + CD2 5 + T细胞比率 (8 4 4 %± 2 39% )显著高于非胸腺切除的MG患者 (5 88%± 2 89% ,P =0 0 38)和健康对照组 (4 5 3%± 0 96 % ,P =0 0 0 3)。提示MG患者外周血中存在异常比例的CD4 + CD2 5 + 调节性T细胞 ,可能参与疾病的发生与发展。     

NOD小鼠自然状态下CD4~+CD25~+T细胞的动态变化及意义

研究自发的1型糖尿病雌鼠模型(NOD)在自然状态下发生1型糖尿病过程中CD4+CD25+T细胞的动态变化,旨在初步探讨调节性T细胞参与1型糖尿病发病的可能机制。采用雌性NOD小鼠作动物模型,每2周尾静脉采血1次,采用三色流式细胞术测定NOD小鼠外周血中CD4+CD25+T细胞(CD3+CD4+CD25+)的百分率。在32周时,对比发生糖尿病和未发生糖尿病NOD小鼠不同脏器中的CD4+CD25+T细胞阳性率。HE法检测胰岛炎。结果显示:(1)自第6周起NOD小鼠CD4+CD25+T细胞百分率逐渐降低。发生糖尿病NOD小鼠CD4+CD25+T细胞比率低于未发病NOD小鼠对照组(外周血分别为0.94%±0.21%、1.62%±0.23%,P=0.01;脾脏2.09%±0.14%、2.77%±0.36%,P=0.019),提示糖尿病NOD小鼠外周血中存在异常比例的CD4+CD25+T细胞;(2)32周龄糖尿病NOD小鼠与未发病NOD小鼠的CD4+CD25+T细胞抑制功能减低,与阳性对照组有显著性差异;(3)HE染色结果示糖尿病NOD小鼠胰岛结构完全破坏,胰岛炎程度较未发病NOD小鼠严重。该结果提示NOD小鼠发生糖尿病时免疫功能紊乱与CD4+CD25+T细胞参与调节及T细胞亚群变化相关,糖尿病的发生受致病性T细胞和调节性T细胞的调节。     

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。     

肺癌患者CD4+ CD25+调节性T细胞的检测及临床意义

目的:检测肺癌患者外周血CD4 CD25 调节性T细胞的分布并探讨相关机制.方法:采用流式细胞仪分析66例肺癌患者外周血CD4 CD25 调节性T细胞占CD4 T淋巴细胞的比例.结果:66例肺癌患者外周血中CD4 CD25 调节性T细胞占CD4 T淋巴细胞的比例为(16.2±2.4)%,与对照组(6.19±1.5)%比较差异有显著性(P＜0.05). 25例鳞癌、29例腺癌、12例小细胞癌患者外周血中CD4 CD25 调节性T细胞比例分别为(18.3±2.9)%、(15.6±1.8)%、(17.3±2.2)%,各组间比较差异无显著性(P＞0.05);均显著高于对照组(6.19±1.5)%,P＜0.05;34例Ⅲ期,14例Ⅳ期肺癌患者外周血中CD4 CD25 调节性T细胞比例为(15.3±2.6)%,(20.4±3.1%),均显著高于18例Ⅱ期患者(9.4±1.3)%,P均＜0.05.结论:肺癌患者外周血中有CD4 CD25 调节性T细胞比例增高,且与分期有关.它可能与肺癌患者免疫功能受损有关,可作为评估肺癌患者预后的一项指标.     

胃癌患者外周血CD4^＋ CD25^high Foxp3^＋调节性T细胞的检测及临床意义

目的:研究CD4+CD25highFoxp3+调节性T细胞(Treg)在胃癌患者外周血单个核细胞(PBMC)的比例变化,探讨其在抗肿瘤免疫调节中的作用及临床意义.方法:采用流式细胞术检测37例胃癌患者治疗前后PBMC中CD4+CD25+/CD4+、CD4+CD25high/CD4+T细胞比例,以及 CD4+CD25+及CD4+CD25highT细胞中Foxp3+T细胞的比例,并与30例正常人对照组的上述指标进行比较.结果:胃癌患者治疗前PBMC中CD4+CD25+/CD4+、CD4+CD25high/CD4+T细胞比例以及CD4+CD25+及CD4+CD25highT细胞中Foxp3阳性表达细胞的水平较正常人对照组明显增高(P＜0.05),治疗后上述指标较治疗前明显减低(P＜0.05), 虽仍高于正常对照组,但差异无显著性(P＞0.05).结论:胃癌患者外周血调节性T细胞比例增高,可能是其免疫功能异常的主要原因之一.     

急性髓系白血病患者外周血CD4+CD25highFOXP3+调节性T细胞变化及临床意义

目的:观察急性髓系白血病(Acute myelogenous leukemia,AML)患者外周血中调节性T细胞(Regulatory T cells,Treg细胞)的变化,探讨其在AML发病中的作用及临床意义.方法:应用流式细胞术检测31例初诊AML患者(初诊组)、23例经化疗取得完全缓解患者(CR组)及20例健康人群(对照组)外周血CD4+CD25highFOXP3+ Treg细胞、CD4+FOXP3+ T细胞占CD4+细胞的比例,同时还分析了外周血CD4+/CD8+比值、NK细胞及血清乳酸脱清酶(LDH)水平.结果:与对照组相比较,AML患者初诊组及CR组外周血CD4+CD25highFOXP3+ Treg细胞和CD4+FOXP3+ T细胞均升高(P＜0.01).与初诊组相比较,CR组CD4+CD25highFOXP3+ Treg细胞无显著降低(P＞0.05),CD4+FOXP3+T细胞明显下降(P＜0.01).CD4+CD25highFOXP3+ Treg细胞的升降与CD4+FOXP3+T细胞呈正相关(r=0.86;P＜0.01).CD4+CD25highFOXP3+ Treg细胞及CD4+FOXP3+ T细胞比例与CD4+/CD8+比值呈负相关(r分别为-0.54、-0.52;P＜0.01)、与NK细胞比例呈负相关(r分别为-0.41、-0.43;P＜0.05),而与LDH水平呈正相关(r分别为0.51、0.57;P＜0.05).结论:CD4+CD25highFOXP3+ Treg细胞增多可能是AML患者免疫功能受抑的重要原因之一,其变化对于AML的预后判断有一定的意义.CD4+FOXP3+ T细胞的作用类似于CD4+CD25highFOXP3+ Treg细胞,其在AML疗效评价方面可能更有价值.     

Study of TNF

目的和方法探讨溃疡性结肠炎(UC)之肿瘤坏死因子α与T细胞亚群的变化及其相关性,测定25例溃疡性结肠炎患者外周血单个核细胞(PBMC)经培养于体外自发和经LPS诱生的TNFα含量及其外周血T细胞亚群百分率和比值.结果①UC组与对照组自发产生的TNFα含量间无明显差异(P＞0.05).LPS诱生后TNFα含量UC组明显低于对照组(P＜0.05).②UC组与对照组CD3细胞百分率无明显差异(68.86%±4.10%vs70.10%±5.04%,P＞0.05).UC组CD4细胞显著低于对照组(32.72%±6.06%vs41.15%±7.26%,P＜0.01),而其CD8细胞则高于对照组(24.96%±4.02%vs21.88%±4.17%,P＜0.05),使得其CD4/CD8的比值明显低于对照组(P＜0.01).③两组诱生后的TNFα含量与其CD4、CD8、CD4/CD8之间均无相关性.结论UC患者TNFα的诱生能力低下,T细胞亚群数量及比值异常,TNFα诱生水平与T细胞亚群的变化间无相关性.     

胃癌患者不同区域淋巴结和外周血CD4~+CD25~+Foxp3~+调节性T细胞的表达和临床意义

目的探讨胃癌患者不同区域淋巴结及外周血中CD4+CD25+Foxp3+调节性T细胞(Tregs)频数变化和临床意义。方法收集45例胃癌患者不同区域淋巴结及外周血标本,采用流式细胞仪检测各标本中Tregs占CD4+T细胞比例,并与胃癌TNM分期、分化程度等参数进行相关性分析。结果 Tregs在引流区阳性淋巴结、引流区阴性淋巴结、非引流区淋巴结、外周血中比例分别为(20.71±2.72)%、(14.43±2.62)%、(10.09±2.27)%、(9.72±2.13)%,前3组中两两相比均差异显著(P0.05),后2组相比无显著差异(P0.05)。引流区阳性淋巴结中Tregs细胞比例与肿瘤分期无显著相关(P0.05);引流区阴性淋巴结、非引流区淋巴结、外周血中Tregs细胞比例与肿瘤分期相关(r=0.429、0.453、0.367;P0.05),且Ⅲ+Ⅳ期Tregs比例显著高于Ⅰ+Ⅱ期比例。不同区域淋巴结Tregs分布与年龄、性别、肿瘤部位、病理分化间差异无相关性。结论 Tregs在不同区域淋巴结及外周血中分布表达呈递减趋势,可能是导致胃癌淋巴结微环境内出现局部免疫抑制,导致肿瘤细胞发生免疫逃逸的重要因素。     

探讨梅毒IL-10、CD4+CD25+表达与预后的关系

目的 探讨梅毒患者外周血CD4+ CD25+调节性T细胞、血清白细胞介素-10(IL-10)的表达变化及其临床意义.方法 以本院皮肤性病科收治的67例确诊梅毒患者作为病例组,30名健康人群作为健康组,采用流式细胞仪技术检测两组研究对象外周血中CD4+ CD25+调节性T细胞、T淋巴细胞亚群水平,采用双抗体夹心酶联免疫吸附法(DABS-ELISA)测定两组研究对象血清IL-10的水平差异.结果 病例组患者的CD4+ CD25+ (12.64 ±3.86)％、CD8+ (28.27±1.86)％,显著的高于健康组(P＜0.05);病例组患者的CD4+ (31.25±6.14)％、CD4+/CD8+ (1.11 ±0.36)％,显著低于健康组患者(P＜0.05).病例组患者的IL-10 4.89±0.41pg/mL显著的高于健康组(P＜0.05).血清固定梅毒患者的CD4+CD25+、CD8+显著的高于Ⅰ期梅毒、Ⅱ期梅毒、潜伏期梅毒患者(P＜0.05),血清固定梅毒患者的CD4+、CD4+/CD8+显著低于Ⅰ期梅毒、Ⅱ期梅毒、潜伏期梅毒患者(P＜0.05).血清固定型患者的血清IL-10 5.02±0.40pg/mL显著的高于Ⅰ期梅毒、Ⅱ期梅毒(P＜0.05).结论 梅毒患者外周血CD4+ CD25+调节性T细胞、IL-10水平显著升高,同时血清固定患者的升高最显著,这可能与患者的免疫抑制具有一定的关系.     

糖皮质激素吸入对哮喘患儿外周血CD4+CD25+ 调节性T细胞水平的影响

目的： 探讨糖皮质激素吸入对哮喘患儿外周血CD4+CD25+ 调节性T细胞（Tr）水平的影响。方法：采用糖皮质激素吸入治疗70例发作期哮喘患儿,应用流式细胞术检测患儿外周血的Tr细胞数。结果：糖皮质激素规则治疗后患儿外周血CD4+CD25+Tr水平（7.05%±1.61%）明显高于治疗前（5.62%±1.29%）,P<0.01。完全控制组患儿外周血CD4+CD25+Tr水平最高（7.56%±1.88%）,部分控制组患儿次之（7.09%±1.23%）,控制不佳组患儿最低（6.11%±1.96%）,差异均显著,P<0.05。经激素规则治疗的患儿外周血Tr水平（7.05%±1.61%）明显高于不规则治疗组患儿（5.91%±1.76%）,P<0.01。结论：规则使用糖皮质激素吸入疗法可明显提高哮喘患儿外周血Tr水平,Tr水平与哮喘的激素治疗效果有关。     

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.     

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.     

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.     

Ontogeny of Tumor-associated CD4+CD25+Foxp3+ T-regulatory Cells

ABSTRACT

The critical contribution of CD4+CD25+Foxp3+ T-regulatory cells (Treg) to immune suppression in the tumor microenvironment is well-established. Whereas the mechanisms that drive the generation and accumulation of Treg in tumors have been an active area of study, the information on their origin and population dynamics remains limited. In this review, we discuss the ontogeny of tumor-associated Treg in light of the recently identified lineage markers.     

Imbalance of CD4+CD45R+ and CD4+CD29+ T helper cell subsets in patients with atopic diseases.

To evaluate the proportion of helper cell subsets we studied 18 children with atopic dermatitis, 30 patients with asthma, 27 healthy age-matched controls aged 1 to 17 years and 11 atopic controls without symptoms related to atopy, aged 9-22 years. Lymphocytes were isolated from heparinized peripheral blood and the proportion of CD4+CD29+ and CD4+CD45R+ cells was determined by double-labelling immunofluorescence. Children with atopic dermatitis yielded a significantly (P less than 0.01) higher proportion of CD4+CD45R+ (median 75%) cells compared with normal controls (median 66.6%), whereas the proportion of CD4+CD29+ cells was significantly (P less than 0.01) lower in patients with atopic dermatitis (median 20.4 versus 29.6%). Interestingly, the percentage of CD4+CD45R+ cells shows an age-dependent decline (r = -0.67, P less than 0.01) in the control group, which is not found in the patient group.     

Phenotypic and functional characteristics of CD4+ CD39+ FOXP3+ and CD4+ CD39+ FOXP3neg T-cell subsets in cancer patients

Human CD4(+) CD39(+) regulatory T (Treg) cells hydrolyze exogenous adenosine triphosphate (ATP) and participate in immunosuppressive adenosine production. They contain two T-cell subsets whose role in mediating suppression is not understood. Frequencies of both CD4(+) CD39(+) subsets were evaluated in peripheral blood lymphocytes of 57 cancer patients and in tumor infiltrating lymphocytes (TILs) of 6 patients. CD4(+) CD39(+) and CD4(+) CD39(neg) T cells isolated using immunobeads and cell sorting were cultured under various conditions. Their conversion into CD39(+) FOXP3(+) CD25(+) or CD39(+) FOX(neg) CD25(neg) cells was monitored by multiparameter flow cytometry. Hydrolysis of exogenous ATP was measured in luminescence assays. Two CD4(+) CD39(+) cell subsets differing in expression of CD25, FOXP3, CTLA-4, CD121a, PD-1, latency associated peptide (LAP), glycoprotein A repetitions predominant (GARP), and the cytokine profile accumulated with equal frequencies in the blood and tumor tissues of cancer patients. The frequency of both subsets was significantly increased in cancer. CD39 expression levels correlated with the subsets' ability to hydrolyze ATP. Conventional CD4(+) CD39(neg) T cells incubated with IL-2 + TGF-β expanded to generate CD4(+) CD39(+) FOXP3(+) Treg cells, while CD4(+) CD39(+) FOXP3(neg) CD25(neg) subset cells stimulated via the TCR and IL-2 converted to FOXP3(+) CTLA4(+) CD25(+) TGF-β-expressing Treg cells. Among CD4(+) CD39(+) Treg cells, the CD4(+) CD39(+) FOXP3(neg) CD25(neg) subset serves as a reservoir of cells able to convert to Treg cells upon activation by environmental signals.     

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.