CD4+CD25+调节性T细胞与克罗恩病发病关系

目的研究克罗恩病（CD）患者外周血白细胞介素（IL）-6水平与外周CD4＋CD25^＋调节性T细胞（Treg细胞）频率及体外抑制功能的变化在CD发病中的作用。方法应用流式细胞术检测CD患者与正常对照者外周CD4^＋CD25^＋Treg细胞的频率及表型以及特征性标志叉状头／翅膀状螺旋转录因子（Foxp3）的表达，同时通过MACS缓冲液分选出外周血CD4^＋CD25^＋T细胞和CD4＋CD25^-T细胞，应用[^3H]-胸腺嘧啶渗入法研究CD4^＋CD25^＋T细胞对自体CD4^＋CD25^-效应T细胞增殖的抑制能力。酶联免疫吸附法（ELISA）检测外周血IL-6水平。结果活动性CD患者外周血IL-6水平显著高于非活动性患者及正常对照者。活动性CD患者外周CD4^＋T细胞中CD4^＋CD25^＋Foxp3^＋T细胞的频率显著低于非活动性CD患者，差异有统计学意义。体外抑制功能试验同样提示活动性CD患者的CD4^＋CD25^＋Treg细胞抑制功能减弱。结论CD4^＋CD25^＋Treg细胞抑制功能减弱与CD发病可能有关，可初步解释CD患者出现的免疫耐受缺失现象。     

SLE患者外周血CD4+ CD25+调节性T细胞及相关基因Foxp3的变化

目的研究系统性红斑狼疮（SLE）合并狼疮性肾炎患者经肾上腺糖皮质激素（简称激素）冲击治疗后，外周血CD4^＋CD25^＋调节性T细胞（regulatoryTcell，Treg）及相关基因Foxp3表达的变化，从而探讨CD4^＋CD25^＋Treg和Foxp3与SLE发病的相关性。方法采用流式细胞术检测SLE患者外周血单个核细胞（PBMC）中CD4^＋CD25^＋T、CD4^＋CD25highT细胞数量的变化，RTPCR检测PBMC中CD4^＋CD25^＋Treg功能相关基因Foxp3mRNA的表达。结果激素冲击治疗后的SLE患者CD4^＋CD25^＋T／CD4^＋T及CD4^＋CD25highT／CD4^＋T比值高于正常对照组；Foxp3mRNA水平表达与对照组差异不显著。结论CD4^＋CD25^＋Treg数量和功能的变化可能参与SLE的发病，激素可能通过提升CD4^＋CD25^＋Treg治疗SLE。     

系统性红斑狼疮患者外周血CD4^＋CD25^＋highCD127lowTreg和CD4^＋CD25^＋Treg水平测定及分析

目的观察系统性红斑狼疮（SLE）患者外周血CD4^＋CD25highCD127low调节性T细胞（Treg）和CD4^＋CD2^＋5Treg水平变化。方法用流式细胞术检测15例活动期SLE患者（SLE组）及20例健康查体者（对照组）外周血淋巴细胞亚群及CD4^＋CD25highCD127lowTreg、CD4^＋CD2^＋5Treg水平。结果 SLE组外周血中T细胞、B细胞及NK细胞比例与对照组比较无显著差异;SLE组外周血CD4^＋CD25highCD127lowTreg和CD4^＋CD2^＋5Treg水平均显著高于对照组（P〈0.05）。结论活动期SLE患者外周血中CD 4^＋CD25 highCD127 lowTreg和CD 4^＋CD 2^＋5 Treg水平显著升高;此是否与应用免疫抑制剂致患者发生自身免疫逃逸有关尚待进一步探讨。     

乙型肝炎患者外周血CD4+ CD25+调节性T细胞表型与功能分析

目的 观察急、慢性乙型肝炎(AHB、CHB)患者外周血CD4+CD25 high调节性T细胞(Treg)的频率、表型和功能特点.方法 采集16例AHB急性发病期(发病后第1周)患者、72例CHB患者和32例健康人的外周血,检测Treg频率,并分析其表面CD45RO、CD45RA、HLA-DR、CD95和细胞内细胞毒T淋巴细胞相关抗原4(CTLA-4)的表达水平.应用实时荧光定量RT-PCR检测CD4+ CD25+、CD4+ CD25-、CD4+和CD4-等细胞亚群和外周血单个核细胞(PBMC)的FoxP3 mRNA表达量.通过MACS免疫磁珠分选Treg,并应用[3H]掺入法检测Treg抑制抗-CD3抗体和HBV抗原刺激的PBMC增殖能力,并观察Treg对HBV抗原或抗-CD3抗体刺激自体PBMC分泌IFNγ的影响.结果 CD4+CD25 high Treg高表达CD45RO、HLA-DR、CD95和细胞内CTLA-4,低表达CD45RA,并且较特异的高表达FoxP3 mRNA.乙型肝炎病人外周血Treg频率与健康对照(3.50±0.72)%比较无统计学差异,但CHB组(3.90±1.44)%显著高于AHB组(3.10±0.87)%,P＜0.05.Treg本身对于HBV抗原或抗-CD3抗体刺激没有明显的增殖反应和IFNγ分泌,但可抑制自体PBMC增殖和IFNγ分泌,其中对HBV抗原刺激引起的细胞反应抑制作用较强.结论 HBV感染者外周血Treg较特异地表达FoxP3分子,能抑制HBV抗原特异性细胞免疫反应,这对于深入阐明CHB发病机制具有重要意义.     

抗肿瘤坏死因子-α治疗对强直性脊柱炎患者外周血CD4+CD25+T细胞调节作用的初步研究

目的 探讨CD4^＋CD25^＋T调节细胞（Treg）在强直性脊柱炎（AS）患者发病机制中的作用，并通过其在抗肿瘤坏死因子（TNF）-α治疗前后的变化，了解抗TNF-α制剂治疗AS的免疫学机制。方法 纳入的10例AS患者均符合1984年修订的纽约标准。治疗使用重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白（rh TNFR—Fc）腹部皮下注射，50mg，每周1次×8周。健康志愿者10名，分别抽取外周血10ml，常规分离淋巴细胞惮核细胞。用流式细胞仪检测CD4^＋CD25^＋T细胞、CD4^＋CD25^high T细胞数量、CTLA-4表达。结果治疗前AS患者外周血中CD4^＋CD25^＋Treg/CD4^＋T为（24＋9）％，高于健康志愿者和经rhTNFR—Fc治疗后的患者（P均〈0．05）。AS患者CD4^＋CD25^high／CD4^＋T淋巴细胞为（6±6）％，亦高于健康志愿者和经rhTNFR—Fc治疗后的AS患者（P均〈0．05）。AS患者CTLA-4为0．15±0．15，高于健康志愿者和治疗后AS患者（P均〈0．05）。结论 在AS患者外周血中CD4^＋CD25^＋Treg数量升高可能参与了AS的发病。CD4^＋CD25^＋Treg数量的变化在一定程度上表现出对于抗TNF-α治疗前后病情的评估作用。     

肝细胞癌患者肝脏组织中CD4+CD25+调节性T淋巴细胞的表达及意义

目的探讨CD4^＋CD25^＋调节性T淋巴细胞在肝细胞癌患者肝脏组织中的表达及意义。方法利用流式细胞仪对31例肝细胞癌患者肝脏组织及末梢静脉血、15份正常肝脏组织、48名正常人末梢静脉血中的CD4^＋CD25^＋调节性T淋巴细胞、CD8^＋T淋巴细胞进行定量及量化关系分析,同时对肝脏组织中CD4^＋CD25^＋调节性T淋巴细胞进行定位分析。结果肝组织CD4^＋CD25^＋调节性T淋巴细胞含量：肝细胞癌组肿瘤周围组织为10．8%±2．3%,远离肿瘤部位组织为4．6%±0．9%、15份正常人肝脏组织为6．0%±0．6%,肿瘤周围组织和远离肿瘤部位组织与正常对照组相比,t值分别为2．05和2．04,P值均＜0．05,差异有统计学意义。外周血中CD4^＋CD25^＋调节性T淋巴细胞含量：肝细胞癌组末梢静脉血中为9．4%±1．0%,正常对照组为12．9%±1．3%,t=13．05,P＜0．01,差异有统计学意义。在肿瘤周围随着CD4^＋CD25^＋调节性T淋巴细胞的增加,CD8^＋T淋巴细胞出现了减少的趋势。结论CD4^＋CD25^＋调节性T淋巴细胞通过对CD8^＋T淋巴细胞的抑制参与肝癌细胞抗肿瘤免疫的作用。     

HBV感染者外周血CD4^＋CD25^＋调节性T细胞的表达水平及临床意义

目的比较CD4^＋CD25^＋FoxP3^＋和CD4^＋CD25^＋CD127^-/low两种设门方法对CD4^＋CD25^＋调节性T细胞（Treg）细胞的界定效果,并探讨HBV感染者外周血中Treg水平的表达及其临床意义。方法选择慢性乙型肝炎患者52例,HBV携带者24例,非活动性HBsAg携带者24例,正常对照者25例,采用CD4^＋CD25^＋CD127^-/low设门方法用流式细胞仪进行检测,其中正常对照组和21例慢性乙型肝炎患者同时采用CD4^＋CD25^＋FoxP3^＋设门进行检测并分析。结果采用CD4^＋CD25^＋CD127^-/low设门方法检测外周血Treg与CD4^＋CD25^＋FoxP3^＋设门方法在正常组和患者组均呈正相关（r=0.506,P〈0.05;r=0.556,P〈0.01）。以CD4^＋CD25^＋CD127^-/low设门检测慢性乙型肝炎患者组、HBV携带者组、非活动性HBsAg携带者组和正常对照组外周血Treg的水平分别为（10.65±2.86）%、（8.56±2.01）%、（8.75±3.04）%和（7.33±1.17）%。慢性乙型肝炎患者组明显高于其他三组（P〈0.01）,慢性HBV携带者组明显高于对照组（P〈0.05）,非活动性HBsAg携带者组与对照组之间差异无统计学意义。慢性乙型肝炎患者及慢性HBV携带者Treg表达水平与HBV病毒载量之间均无相关,慢性乙型肝炎患者Treg表达水平与ALT之间无相关,HBeAg阳性患者组和HBeAg阴性患者组的Treg表达水平差异无统计学意义。结论 CD4^＋CD25^＋CD127^-/low设门方法检测外周血Treg与CD4^＋CD25^＋FoxP3^＋设门方法有较好的相关性,而前者更为简单、实用。Treg在慢性乙型肝炎患者、慢性HBV携带者中明显增高,提示Treg在乙型肝炎慢性化机制中发挥重要作用。     

系统性红斑狼疮患者外周血CD4+CD25+FOXP3+调节性T细胞的检测和意义

目的检测系统性红斑狼疮（SEE）患者外周血CD4^＋CD25^＋FOXP3^＋调节性T细胞（Treg）的百分比，并分析其与疾病活动的相关性。方法采用流式细胞仪检测28例SLE患者（其中活动组18例）及22名正常对照组的外周血CD4^＋CD25^＋FOXP3^＋Treg的百分比，同时评估SLE疾病活动指数（SLEDAI）及检测血抗dsDNA水平，分析相关性。结果SLE患者外周血CD4^＋CD25^＋FOXP3^＋Treg占CD4^＋T细胞的百分比较对照组降低（P〈0．05），以活动组尤为明显，CD4^＋CD25^＋FOXP3^＋Treg的百分比与SLEDAI呈明显的负相关（P〈0．01），同时显示血抗dsDNA阳性组较阴性组患者外周血CD4^＋CD25^＋FOXP3^＋Treg的百分比显著下降（P〈0．01）。结论SLE患者外周血CD4^＋CD25^＋FOXP3^＋Treg的百分比在活动期下降为明显，其在SLE的发病机制中可能起到重要的作用。     

肝细胞癌患者CD8＋T淋巴细胞上PD-1高表达的意义研究

目的了解细胞程序性死亡受体1（programmed death1,PD—1）在HBV相关性肝细胞癌（hepatocellular carcinoma,HCC）患者CD8＋T淋巴细胞上的表达及与疾病状态的关系。方法用流式技术检测58例HBV相关性PHC患者外周血及肝组织中CD8^＋T淋巴细胞上PD-1的表达,并与20例HBV相关性肝硬化患者及20例健康对照者相比较。结果HCC患者外周血CD8^＋T淋巴细胞上PD-1的表达明显上调,与肝硬化组及健康组相比,差异有统计学意义,并且肿瘤区的表达高于非肿瘤区,随着HCC病情的进展而增加。结论PD-1在CD8^＋T淋巴细胞上表达具有负性调节CD8^＋T淋巴细胞活化增殖作用,其表达水平对HCC病情有预测作用。     

CD4+CD25+FOXP3+调节性T细胞在肺癌患者外周血中的表达及意义

选择同期收治的60例肺癌患者（肺癌组）和34例健康查体者（对照组）,利用流式细胞仪检测其外周血CD4^＋CD25^＋FOXP3^＋调节性T细胞表达情况。结果肺癌组外周血CD4^＋CD25^＋FOXP3^＋调节性T细胞表达水平显著高于对照组。认为CD4^＋CD25^＋FOXP3^＋调节性T淋巴细胞可能通过调节机体免疫力参与肺癌的发生、发展,临床可通过抑制或阻断FOXP3表达抑制调节性T细胞的功能,提高机体对肿瘤抗原的免疫应答。     

慢性HBV感染患者外周血CD4~+CD25~+调节性T细胞表达及其临床意义

目的探讨CD4+CD25+调节性T细胞与慢性HBV感染后不同临床转归和临床特点的相关性。方法在26例慢性乙型肝炎(CHB)患者、15例无症状HBsAg携带者(ASC)和11例肝炎肝硬化(LC)患者和16例正常对照者,分离外周血单个核细胞(PBMC),采用流式细胞仪检测CD4+CD25+调节性T细胞的表达水平。结果CHB组和ASC组的CD4+CD25+调节性T细胞占CD4+T细胞的百分率分别为4.40±2.76%和4.43±2.10%,均高于正常对照组(2.70±0.97%),差异显著(P0.01);CD4+CD25+调节性T细胞的表达水平与HBVDNA水平无相关性(r=0.018,P0.05);在HBeAg阳性与阴性组患者CD4+CD25+调节性T细胞的表达也无明显的差异(P0.05)。结论慢性HBV感染者外周血CD4+CD25+调节性T细胞水平升高,可能与HBV感染的慢性化有关。     

Impaired function of CD4+/CD25+ T regulatory lymphocytes characterizes the self-limited hepatitis A virus infection

Background and Aim:  Hepatitis A virus (HAV) causes a transient illness leaving permanent protection against reinfection. Few data are available on the regulatory mechanisms involved in the CD4+ T helper activation. We aimed to investigate the frequency and function of CD3+/CD4+/CD25+ T cells with regulatory function (Tregs) during acute HAV infection.
Methods:  We enrolled 35 consecutive patients and 15 healthy donors, enumerated Tregs by flow cytometry assay and evaluated, after immunomagnetical sorting with magnetic beads, their ability to inhibit the proliferation of CD4+/CD25– T lymphocytes at different ratios (1:1, 1:10, 1:20).
Results:  All patients had the usual course of infection. Our immunological analysis showed Tregs frequency in these patients (6.5% [range, 5–8.8%]; 36 [range, 10–87] cells) did not have any statistical difference compared with healthy donors (6% [range, 5–8%]; 48 (range, 23–71) cells), while their ability to suppress CD4+/CD25– was drastically reduced at different ratios (Mann–Whitney U -test; ratio 1:1, 93% vs 72%, z = −3.34, P  < 0.0001; ratio 1:10, 86% vs 51%, z = −4.04, P  < 0.001; ratio 1:20, 56% vs 30%, z = −3.43, P  < 0.0001). After the seroconversion, CD4+/CD25+ frequency and function in HAV-infected patients did not differ from healthy individuals.
Conclusion:  CD4+/CD25+ T cells seem to be impaired in their function during the HAV acute infection. This evidence might help to determine an optimal T helper cell immune network that is a predisposing factor for a self-limiting disease.     

支气管哮喘患者外周血中的CD+4 CD+25 T淋巴细胞的测定

目的阐明支气管哮喘(简称哮喘)患者外周血中是否存訡D+4 CD+25 T调节性淋巴细胞,并探讨CD+4 CD+25细胞的免疫抑制活性.方法应用流式细胞仪检测29例过敏性哮喘患者[急性发作期患者(急性发作期)15例、缓解期患者(缓解期)14例和16名非过敏性健康志愿者(正常对照组)外周血中CD+4 CD+25 细胞数量变化.应用免疫磁珠法分离提纯CD+4 CD+25 细胞,将纯化的CD+4 CD+25细胞和(或)CD+4 CD-25细胞在体外培养,观察CD+4 CD-25细胞的增殖反应,将收集培养的上清液用酶联免疫吸附测定(ELISA)法检测Th1类细胞因子γ干扰素(IFN-γ)和Th2类细胞因子白细胞介素4(IL-4)和IL-13.结果急性发作期患者外周血中CD+4 CD+25细胞比值为(14.9±1.8)%,缓解期患者为(11.8±0.7)%,正常对照组为(11.2±0.8)%,发作期与缓解期患者比较差异有统计学意义(P<0.01);缓解期患者与正常对照组比较差异无统计学意义(P>0.05).哮喘组CD+4 CD-25细胞增殖反应为(74±9)%,正常对照组为(72±8)%,两组比较差异无统计学意义(P>0.05).此外,哮喘组和正常对照组的CD+4 CD+25 细胞均能抑制CD+4 CD-25细胞产生IFN-γ、IL-4和IL-13,而且两组的抑制能力也无明显区别.结论急性发作期哮喘患者外周血CD+4 CD+25 细胞数明显高于缓解期患者和正常对照组.哮喘患者的CD+4 CD+25 细胞的抑制活性和正常对照组比较差异无统计学意义.谮     

TNF downmodulates the function of human CD4+CD25hi T-regulatory cells

CD4+CD25+ T-regulatory cells (Tregs) play an essential role in maintaining immunologic homeostasis and preventing autoimmunity. However, little is known about the exogenous factors that regulate their differentiation and function. Here, we report that TNF inhibits the suppressive function of both naturally occurring CD4+CD25+ Tregs and TGFbeta1-induced CD4+CD25+ T-regulatory cells. The mechanism of this inhibition involves signaling through TNFRII that is constitutively expressed selectively on unstimulated Tregs and that is up-regulated by TNF. TNF-mediated inhibition of suppressive function is related to a decrease in FoxP3 mRNA and protein expression by the Tregs. Notably, CD4+CD25hi Tregs isolated from patients with active rheumatoid arthritis (RA) expressed reduced levels of FoxP3 mRNA and protein and poorly suppressed the proliferation and cytokine secretion of CD4+ effector T cells in vitro. Treatment with anti-TNF antibody (infliximab) increased FOXP3 mRNA and protein expression by CD4+CD25hi Tregs and restored their suppressive function. Thus, TNF has a novel action in modulating autoimmunity, by inhibiting CD4+CD25+ Treg activity.     

Intraepithelial CD8+ tumor-infiltrating lymphocytes and a high CD8+/regulatory T cell ratio are associated with favorable prognosis in ovarian cancer

In a recent report, [Zhang et al. (2003) N. Engl. J. Med. 348, 203-213], the presence of CD3+ tumor-infiltrating lymphocytes (TILs) was found to correlate with improved survival in epithelial ovarian cancer. We performed immunohistochemical analysis for TILs and cancer testis antigens in 117 cases of epithelial ovarian cancer. The interrelationship between subpopulations of TILs and expression of cancer testis antigens was investigated, as well as between TILs and overall survival. The median follow-up of the patients was 31 months. Patients with higher frequencies of intraepithelial CD8+ T cells demonstrated improved survival compared with patients with lower frequencies [median = 55 versus 26 months; hazard ratio = 0.33; confidence interval (C.I.) = 0.18-0.60; P = 0.0003]. No association was found for CD3+ TILs or other subtypes of intraepithelial or stromal TILs. However, the subgroups with high versus low intraepithelial CD8+/CD4+ TIL ratios had median survival of 74 and 25 months, respectively (hazard ratio = 0.30; C.I. = 0.16-0.55; P = 0.0001). These results indicate that CD4+ TILs influence the beneficial effects of CD8+ TIL. This unfavorable effect of CD4+ T cells on prognosis was found to be due to CD25+ forkhead box P3 (FOXP3)+ regulatory T cells (Treg; suppressor T cells), as indicated by survival of patients with high versus low CD8+/Treg ratios (median = 58 versus 23 months; hazard ratio = 0.31; C.I. = 0.17-0.58; P = 0.0002). The favorable prognostic effect of intraepithelial CD8+ TILs did not correlate with concurrent expression of NY-ESO-1 or MAGE antigens. We conclude that intraepithelial CD8+ TILs and a high CD8+/Treg ratio are associated with favorable prognosis in epithelial ovarian cancer.     

Compromised lymphocytes infiltrate hepatocellular carcinoma: the role of T-regulatory cells

Hepatocellular carcinoma (HCC) has a poor prognosis with limited therapeutic options. We propose that local immune responses in patients with HCC are held in check by tumor-infiltrating CD4(+)CD25(+) T-regulatory lymphocytes (T(reg) cells), which suppress the activity and proliferation of effector CD4(+) and CD8(+) T cells. The phenotype and cell cycle status of tumor-infiltrating lymphocytes (TILs) in HCC were analyzed via immunohistochemistry of sections from patients undergoing surgery for HCC and via flow cytometry of peripheral blood mononuclear cells and TILs isolated from patients with HCC. Circulating and tumor-infiltrating T-cell function and activation status were assessed via proliferation and flow cytometry. More than 96% of TILs were quiescent as measured via Mcm-2 or Ki-67 expression, while less than 10% of CD8(+) T cells expressed perforin or granzyme B. CD4(+)CD25(+) T(reg) cells comprised 8.7% (1.4-13.8) of TILs and always exceeded the proportion in distant nontumor tissue (2.4% [1.5-5.6]; P = .014). T(reg) cells isolated from HCC suppressed proliferation of autologous circulating CD4(+)CD25(-) cells and perforin expression and proliferation of autologous CD8(+) T cells. The proportion of circulating T(reg) cells in patients with HCC was similar in healthy controls (7.2% [1.2-23.3] and 9.2% [1.6-30.2], respectively), but the proportion of circulating T(reg) cells that were also transforming growth factor beta1(+) was elevated in HCC compared with controls (55.5% [8.2-73.9] and 2.0% [0-4.9], respectively; P = .003). In conclusion, TILs are compromised and contain a subpopulation of suppressive CD4(+)CD25(+)Foxp3(+) T(reg) cells. Functional deletion of tumor-infiltrating T(reg) cells could enhance tumor-specific immunotherapy.     

Increase of CD4+ CD25+ regulatory T-cells in the liver of patients with hepatocellular carcinoma

BACKGROUND/AIMS: The immune response to tumor-specific antigens is typically unable to control the growth and spread of malignant cells. Accumulating evidence indicates that the suppressive effects of CD4+ CD25+ regulatory T-cells are at least partially responsible for the failure of immune-mediated elimination of tumor cells. METHODS: We have studied 25 patients with hepatocellular carcinoma (HCC). The liver tissues with HCC were separated into the marginal region of tumor (peri-tumor region) and the non-tumor region distant from the tumor. CD4+ CD25+ T-cells were quantified in the blood and the liver by flow cytometry and immunohistochemistry, and their effect on T-cell proliferation and activation was determined. RESULTS: We found a significant increase in both the proportion and absolute numbers of CD4+ CD25+ T-cells in the peri-tumor regions, but not in unaffected areas (9.5 +/- 4.5 vs. 4.6 +/- 2.8%, P = 0.011). CD4+ CD25+ T-cells isolated from peri-tumor regions displayed phenotype markers characteristic of regulatory T-cells, and expressed Foxp3 mRNA. CD8+ T-cells in peri-tumor regions were inversely proportional to CD4+ CD25+ T-cells in the same region (P < 0.001). Moreover, isolated CD4+ CD25+ T-cells inhibited autologous CD8+ T-cell proliferation. CONCLUSIONS: Our results suggest that CD4+ CD25+ T-cells in the marginal region of HCC may play a critical role in controlling CD8+ cytotoxic T-cell activity and, thereby, contribute to the progression of HCC.     

Functional CD4+CD25high regulatory T cells are enriched in the colonic mucosa of patients with active ulcerative colitis and increase with disease activity

BACKGROUND: Factors determining the extension and degree of inflammation in the colonic mucosa of patients with ulcerative colitis (UC) are largely unknown, but CD4+CD25high regulatory T cells (Tregs) have been implicated to play an important role in suppressing inflammation. Therefore, the aims of this study were to determine whether colonic Tregs have suppressive effects on colonic effector T cells in UC and to analyze the association between segmental colonic Treg distribution and disease activity. MATERIALS AND METHODS: The suppressive activity of colonic CD4+CD25high Tregs from patients with active UC was determined in coculture assays measuring proliferation and cytokine production. The frequency of Tregs and the expression of the Treg marker FOXP3 were analyzed with flow cytometry and RT-PCR in isolated cells and the whole mucosa from patients with active and inactive disease, as well as healthy mucosa. RESULTS: Colonic CD4+CD25high T cells from patients with UC suppressed the proliferation and cytokine secretion of colonic effector CD4+ T cells. Healthy controls but not patients with UC had lower Treg frequencies in the sigmoid than in the ascending colon. Patients with UC with active disease had increased frequency of colonic Tregs. The frequency of Tregs was positively correlated with colonic disease activity and serum C-reactive protein. CONCLUSIONS: Colonic CD4+CD25high Tregs are able to suppress colonic effector T cell activity in vitro, and the Treg frequency in the inflamed intestine increases with disease activity in patients with active UC. This suggests that Tregs may be outnumbered by other inflammatory cells or that their suppressive activity may be influenced by the in vivo environment.