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。     

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。     

诱导缓解治疗对系统性红斑狼疮患者外周血CD4^＋CD25^＋T细胞表达的影响

目的探讨CD4^＋CD25^＋调节性T细胞在系统性红斑狼疮（SLE）患者诱导缓解治疗前后外周血的表达及其临床意义。方法入选28例SLE患者和15例正常对照者（对照组）。用流式细胞仪检测SLE患者和对照组的外周血CD4^＋CD25^＋T细胞阳性率。结果SLE患者在诱导缓解治疗前后CD4^＋CD25^＋调节性T细胞比率均低于对照组（P〈0．05）;诱导缓解治疗后患者外周血CD4^＋CD25^＋调节性T细胞比率较治疗前回升,两者间比较无统计学意义（P〉0．05）;SLE合并肾损害者CD4^＋CD25^＋T细胞比率显著低于未合并肾损害者（P〈0．05）。结论SLE患者外周血CD4^＋CD25^＋调节性T细胞数量显著低于正常人,合并肾损害者更明显,且CD4^＋CD25^＋T细胞比率和狼疮活动性指数之间存在相关性。诱导缓解治疗上调了患者外周血CD4^＋CD25^＋T细胞的数量。     

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。     

抗病毒治疗对慢性丙型肝炎CD4^＋CD25^＋调节性T细胞频率和功能的影响

目的研究抗病毒治疗前后慢性丙型肝炎患者CD4^＋CD25^＋调节性T细胞（Treg）频率和功能的变化。方法筛选HLA—A2阳性慢性丙型肝炎患者31例，给予聚乙二醇化干扰素α-2a（相对分子质量为40000）180μg每周1次皮下注射，联合口服利巴韦林。分别在治疗前和治疗结束随访24周时应用流式细胞仪检测患者CD4^＋CD25^＋ Treg细胞占外周血CD4^＋T细胞的频率，应用液闪计数仪检测其对HCV特异性CD8^＋T细胞增殖的抑制作用，ELISA法检测细胞培养上清γ干扰素（IFN-γ）水平的变化情况。结果治疗结束随访24周，患者外周血CD4^＋CD25^＋ Treg细胞频率为（9．6±3．0）％，明显低于治疗前的（11．0±2．3）％（t=2．028，P〈0．05）；持续病毒学应答（SVR）组CD4^＋CD25^＋ Treg细胞频率为（8．9±2．7）％，明显低于未获得SVR患者组的（10．4±2．3）％（t=3．324，P〈0．01）。抗病毒治疗后CD4^＋CD25^＋ Treg细胞抑制HCV特异性CD8^＋T细胞增殖的作用减弱。治疗后患者IFN-γ水平为（3959±577）pg／ml，明显高于治疗前的（1965±326）pg／ml（t=16．1，P〈0．01）；获得SVR患者组IFN-γ（6824±568）pg／ml，明显高于未获得SVR患者组的（2219±286）pg／ml（t=29．853，P〈0．001）。结论慢性丙型肝炎患者随着HCV RNA水平的下降，CD4^＋CD25^＋Treg细胞频率降低，抑制HCV特异性CD8^＋T细胞增殖的作用减弱。     

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^highCD127^low/-T细胞的表达及其意义△

目的检测系统性红斑狼疮患者外周血CD4^＋CD25^highCD127^low/-T细胞，探讨调节性T细胞（regulatory Tcells，Treg）在系统性红斑狼疮（systemic lupus erythematosus，SLE）发病中的作用。方法采用三色直接荧光素标记法和多参数流式细胞仪检测41例SLE患者及24名正常对照者外周血CD4^＋CD25^T细胞、CD4^＋CD25^highT细胞、CD4^＋CD127^low/-T细胞、CD4^＋CD25^highCD127^low/-T细胞、CD4^＋CD25^highCD127^low/-T细胞的比例。同时检测外周血抗dsDNA等抗体及免疫球蛋白、补体等水平并进行相关分析。结果SLE患者外周血CD4^＋CD25^highCD127^low/-T细胞与正常对照组比较明显减少，差异有统计学意义（P〈0．001）；CD4^＋CD25^highT细胞百分率也低于正常对照组（P〈0．001）；CD4^＋CD25^＋T细胞、CD4^＋CD127^low/-T细胞、CD4^＋CD25^highCD127^low/-T细胞百分率与正常对照组比较无显著性差异（P〉0．05）。五组细胞与患者年龄、性别和病程，IgG、IgA、IgM、尿蛋白，24h蛋白尿，抗dsDNA、抗Sm、抗SSA、抗SSB、抗RNP、抗Clq、抗核小体抗体水平均无相关性（P〉0．05）；CD4^＋CD25^highCD127^low/-T细胞、CD4^＋CD25^＋T细胞、CD4^＋CD127^low/-T细胞与SLEDAI评分无相关性（P〉0．05）．而CD4^＋CD25^highCD127^low/-T细胞及CD4^＋CD25^highT细胞与SLEDAI评分呈负相关（P〈0．05）。CD4^＋CD25^highCD127^low/-T细胞与CD4^＋CD25^highT细胞呈明显正相关（r=0．987，P〈0．001）。结论外周血CD4^＋CD25^highCD127^low/-T细胞异常参与了SLE的发病并与SLE活动性相关；CD4^＋CD25^highCD127^low/-T细胞可能最具Treg细胞表型特征：CD4^＋CD25^highCD127^low/-T细胞可能具有调节和效应双重特性。     

支气管哮喘大鼠CD4^＋CD25^＋T细胞的变化及地塞米松干预作用的研究

目的研究支气管哮喘（简称哮喘）大鼠模型支气管肺泡灌洗液（BALF）、血液、脾脏CD4^＋CD25^＋T细胞的变化,及地塞米松对CD4^＋CD25^＋T细胞的影响。方法50只SD大鼠随机分为5组,空白对照（A）组,哮喘（B）组,地塞米松1（C）组、地塞米松2（D）组,地塞米松3（E）组。A组第1天给予腹腔注射生理盐水1ml,第15～21天每天给予生理盐水雾化。B、C、D、E组用卵蛋白建立哮喘大鼠模型,第1天,每只大鼠腹腔注射抗原1ml（卵蛋白1mg＋灭活百日咳杆菌9×10。个＋氢氧化铝干粉100mg）混悬液,第15～21天给予1％的卵蛋白雾化30min,C、D、E组于雾化后分别给予腹腔注射地塞米松0．2mg／kg、1mg／kg、2mg／kg。采用流式细胞仪检测的方法,观察大鼠体内BALF、外周血、脾脏CD4^＋CD25^＋T细胞的变化及使用不同剂量地塞米松后对其的影响。结果B组BALF、外周血、脾脏CD4^＋CD25^＋T细胞表达占CD4^＋T细胞的百分比分别是（42．21±5．62）％、（12．69±2．70）％、（11．15±1．05）％,A组结果分别是（18．76±5．85）％、（6．21±1．73）％、（7．85±2．13）％。B组与A组比较,差异均具有统计学意义（P〈0．01,P〈0．01,P〈0．05）;C组、D组、E组BALF中CD4^＋CD25^＋T细胞占CD4^＋T细胞的百分比表达分别是（10．49±4．03）oA、（13．28±5．12）％、（7．51±5．39）％,显著低于A组和B组,（P〈0．05,P〈0．01）;外周血中,C组（6．03±1．43）％、D组（4．88±0．95）％与A组（6．21±1．73）％比较,差异无统计学意义,E组（3．49士0．62）％与C组、A组比较,差异有统计学意义（P〈0．05）。脾脏中,c组（7．25±1．82）%、D组（8．63±3．18）％与A组（7．85±2．13）％比较,差异无统计学意义,E组（3．38±1．37）％与C组、D组、A组比较,差异有统计学意义（P〈0．05）。结论CD4^＋CD25^＋T细胞在哮喘大鼠体内有明显的优势表达,可能是哮喘发病的机制之一。地塞米松可以抑制CD4^＋CD25^＋T细胞的表达。BALF内CD4^＋CD25^＋T细胞的变化与外周血和脾脏的变化具有一致性,监测外周血或脾脏CD4^＋CD25^＋T细胞变化可了解肺部情况。     

儿童AITP治疗前后CD4^＋CD25^High Foxp3^＋Treg细胞与Foxp3基因表达的变化

目的探讨CD4^＋CD25^High Foxp3^＋Treg细胞在儿童急性特发性血小板减少性紫癜（AITP）发病中的作用及对丙种球蛋白、激素治疗的效应关系。方法流式细胞仪检测AITP患儿治疗前后CD4^＋CD25^High Foxp3^＋Treg细胞比例变化，RT—PCR法检测外周血单个核细胞中Foxp3mRNA的表达。结果单用激素或联用激素和丙种球蛋白治疗后AITP患儿CD4^＋CD25^High Foxp3^＋Treg细胞比例和Foxp3基因表达水平较治疗前和正常对照组明显增高（P〈0．01），其中联用丙种球蛋白和激素组的增高水平更为明显（P〈0．01）。结论CD4^＋CD25^High Foxp3^＋Treg细胞比例下降及Foxp3基因表达降低是AITP的发病机制之一，丙种球蛋白和激素可以通过诱导其扩增及活化发挥治疗AITP的作用。     

慢性肺源性心脏病患者CD4+CD25+Treg的改变

目的观察慢性阻塞性肺疾病（COPD）所致慢性肺源性心脏病（CPHD）患者急性加重期以及治疗病情缓解后外周血中调节型T细胞（CD4^＋CD25^＋Treg）和血浆中Th1型细胞因子INF-γ及Th2型细胞因子IL-4的水平变化,并与健康对照者外周血中相应指标进行比较。探讨慢性肺源性心脏病患者细胞免疫功能状态,为CPHD患者治疗开辟新的途径。方法对CPHD患者急性加重期及治疗病情缓解后、健康对照者采用流式细胞仪技术检测外周血中的CD4^＋CD25^＋Treg水平。采用酶标记免疫吸附测定法（ELISA）测定血浆中INF-γ、IL-4的浓度。结果 CD4^＋CD25^＋Treg在CPHD急性期组高于缓解组和健康对照组,缓解组低于健康对照组（P〈0.05）。CPHD患者血浆中INF-γ在急性期组高于缓解组和健康对照组,缓解组高于健康对照组（P〈0.05）。CPHD患者急性期组、缓解组与健康对照组三组之间血浆IL-4的差别无统计学意义。结论 CPHD患者急性加重期和治疗病情缓解后均存在免疫功能的低下和免疫功能的失调。     

Human CD8+CD25+ thymocytes share phenotypic and functional features with CD4+CD25+ regulatory thymocytes

CD8+CD25+ cells, which expressed high levels of Foxp3, glucocorticoid-induced tumor necrosis factor receptor (GITR), CCR8, tumor necrosis factor receptor 2 (TNFR2), and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) mRNAs, were identified in the fibrous septa and medullary areas of human thymus. Activated CD8+CD25+ thymocytes did not produce cytokines, but most of them expressed surface CTLA-4 and transforming growth factor beta1 (TGF-beta1). Like CD4+CD25+, CD8+CD25+ thymocytes suppressed the proliferation of autologous CD25-T cells via a contact-dependent mechanism. The suppressive activity of CD8+CD25+ thymocytes was abrogated by a mixture of anti-CTLA-4 and anti-TGF-beta1 antibodies and it was mediated by their ability to inhibit the expression of the interleukin 2 receptor alpha chain on target T cells. These results demonstrate the existence of a subset of human CD8+CD25+ thymocytes sharing phenotype, functional features, and mechanism of action with CD4+CD25+ T regulatory cells.     

非小细胞肺癌患者CD3+、CD4+、CD8+、CD44+表达的临床研究

目的研究非小细胞肺癌患者外周血淋巴细胞中CD3+、CD4+、CD8+、CD4+4的表达水平。方法取65例非小细胞肺癌患者及22例健康正常人外周静脉血,应用流式细胞仪检验非小细胞肺癌患者(实验组)与健康人外周血淋巴细胞中(对照组)CD3+、CD4+、CD8+、CD4+4的表达水平。结果实验组与对照组CD3+、CD3+CD4+、CD3+CD8+、CD4+4在淋巴细胞中的比例存在显著性差异(P<0.05),其中,实验组占总淋巴细胞的比例分别为48.07±10.33%、30.93±6.68%、17.13±3.37%、55.45±4.35%;对照组CD3+、CD3+CD4+、CD3+CD8+、CD4+4占总淋巴细胞的比例分别为58.83±10.88%、34.89±6.45%、23.91±4.42%、62.85±7.56%;但鳞癌与腺癌组CD4+4的表达无显著性差异(P>0.05),其中,鳞癌组CD4+4所占比例为61.32±8.06%,腺癌组为64.43±6.76%。结论非小细胞肺癌患者外周血T细胞亚群及CD4+4的表达水平较正常组均低,其表达水平与组织类型无关。     

CD19+CD5+ cells as indicators of preeclampsia

Preeclampsia is a devastating pregnancy-associated disorder affecting 5% to 8% of pregnant women worldwide. It emerges as an autoimmune-driven disease, and, among others, the autoantibodies against angiotensin type 1 receptor II have been proposed to account for preeclampsia symptoms. Despite much attention focused on describing autoantibodies associated with preeclampsia, there is no clue concerning the cell population producing them. CD19(+)CD5(+) B-1a B cells constitute the main source of natural and polyreactive antibodies, which can be directed against own structures. Here, we aimed to identify the B-cell subpopulation responsible for autoantibody production during preeclampsia and to study their regulation, as well as their possible use as markers for the disease. The frequency of CD19(+)CD5(+) cells in peripheral blood of preeclamptic patients is dramatically increased compared with normal pregnant women as analyzed by flow cytometry. This seems to be driven by the high human chorionic gonadotropin levels present in the serum and placenta supernatant of preeclamptic patients versus normal pregnant women. Not only ≈95% of CD19(+)CD5(+) cells express the human chorionic gonadotropin receptor, but these cells also expand on human chorionic gonadotropin stimulation in a lymphocyte culture. Most importantly, isolated CD19(+)CD5(+) cells produce autoantibodies against angiotensin type 1 receptor II, and CD19(+)CD5(+) cells were further detected in the placenta of preeclamptic but not of normal pregnancies where barely B cells are present. Our results identify a B-cell population able to produce pregnancy-pathological autoantibodies as possible markers for preeclampsia, which opens vast diagnostic and therapeutic applications.     

Decrease in CD4+CD25+ and CD8+CD28+ T cells in interstitial pneumonitis associated with rheumatic disease

The expression of CD25 or CD28 on T cells was examined in patients with rheumatic diseases associated with interstitial pneumonitis (IP), in order to investigate the conditions of CD4⁺CD25⁺ regulatory T cells and CD8⁺CD28⁻ suppressor T cells. Fifty-five patients with various rheumatic diseases and 23 normal controls were enrolled. CD4⁺CD25⁺ T cells of patients with IP were significantly decreased in comparison with non-IP patients, and the ratio of CD8⁺CD28⁻ T cells in patients with IP was significantly higher than that in non-IP patients or normal controls. These results for CD8⁺CD28⁻ T cells were in accord with the decrease in CD8⁺CD28⁺ T cells, and may be related to activation-induced CD8⁺CD28⁺ T-cell death. Thus, the abnormality of CD4⁺CD25⁺ regulatory T cells may be related to the pathogenesis of IP, and the survival and activation of CD8⁺ T cells.     

Decrease in CD4+CD25+ and CD8+CD28+ T cells in interstitial pneumonitis associated with rheumatic disease

Abstract

The expression of CD25 or CD28 on T cells was examined in patients with rheumatic diseases associated with interstitial pneumonitis (IP), in order to investigate the conditions of CD4⁺CD25⁺ regulatory T cells and CD8⁺CD28^? suppressor T cells. Fifty-five patients with various rheumatic diseases and 23 normal controls were enrolled. CD4⁺CD25⁺ T cells of patients with IP were significantly decreased in comparison with non-IP patients, and the ratio of CD8⁺CD28^? T cells in patients with IP was significantly higher than that in non-IP patients or normal controls. These results for CD8⁺CD28^? T cells were in accord with the decrease in CD8⁺CD28⁺ T cells, and may be related to activation-induced CD8⁺CD28⁺ T-cell death. Thus, the abnormality of CD4⁺CD25⁺ regulatory T cells may be related to the pathogenesis of IP, and the survival and activation of CD8⁺ T cells.     

CD11c+CD88+CD317+ myeloid cells are critical mediators of persistent CNS autoimmunity

Natalizumab, a humanized monoclonal antibody (mAb) against α4-integrin, reduces the number of dendritic cells (DC) in cerebral perivascular spaces in multiple sclerosis (MS). Selective deletion of α4-integrin in CD11c⁺ cells should curtail their migration to the central nervous system (CNS) and ameliorate experimental autoimmune encephalomyelitis (EAE). We generated CD11c.Cre^+/−ITGA4^fl/fl C57BL/6 mice to selectively delete α4-integrin in CD11c⁺ cells. Active immunization and adoptive transfer EAE models were employed and compared with WT controls. Multiparameter flow cytometry was utilized to immunophenotype leukocyte subsets. Single-cell RNA sequencing was used to profile individual cells. α4-Integrin expression by CD11c⁺ cells was significantly reduced in primary and secondary lymphoid organs in CD11c.Cre^+/−ITGA4^fl/fl mice. In active EAE, a delayed disease onset was observed in CD11c.Cre^+/−ITGA4^fl/fl mice, during which CD11c⁺CD88⁺ cells were sequestered in the blood. Upon clinical EAE onset, CD11c⁺CD88⁺ cells appeared in the CNS and expressed CD317⁺. In adoptive transfer experiments, CD11c.Cre^+/−ITGA4^fl/fl mice had ameliorated clinical disease phenotype associated with significantly diminished numbers of CNS CD11c⁺CD88⁺CD317⁺ cells. In human cerebrospinal fluid from subjects with neuroinflammation, microglia-like cells display coincident expression of ITGAX (CD11c), C5AR1 (CD88), and BST2 (CD317). In mice, we show that only activated, but not naïve microglia expressed CD11c, CD88, and CD317. Finally, anti-CD317 treatment prior to clinical EAE substantially enhanced recovery in mice.

Autoimmune disorders of the central nervous system (CNS), including multiple sclerosis (MS), are thought to be mediated by aberrant adaptive immune responses against self-antigens. In experimental autoimmune encephalomyelitis (EAE), a model of MS, activated myelin-reactive CD4⁺ T helper cells are the main drivers of disease activity (1). In active EAE, dendritic cells (DC) are professional antigen-presenting cells (APC) at the inoculation site, namely in draining lymph nodes and other secondary lymphoid organs, where they present myelin autoantigen to naïve CD4⁺ T lymphocytes (2). Myeloid APC within the CNS are essential for the reactivation and retention of these autoreactive CD4⁺ T cells, and for perpetuation of disease activity. Specifically, myeloid cells within cerebral perivascular spaces previously considered DC based solely on their expression of CD11c are sufficient to permit EAE (3). Myeloid APC, including DC, use α4-integrin to gain access to sites of ongoing inflammation. We previously showed that the number of DC was significantly reduced in cerebral perivascular spaces in autopsy material of an MS patient treated with natalizumab, a humanized monoclonal antibody (mAb) against α4-integrin (4). Conceivably, antagonizing or diminishing the function of α4-integrin selectively in myeloid cells should ameliorate EAE through an impaired reactivation of CNS-specific CD4⁺ T cells and a reduction of direct inflammatory effects exerted by these cells.To further understand the role of CD11c⁺ cells within the CNS during CD4⁺ T cell-mediated CNS autoimmunity, we generated and characterized CD11c.Cre^+/−ITGA4^fl/fl mice, which lack α4-integrin expression in CD11c⁺ cells. We identified CD11c⁺CD88⁺CD317⁺ as mediators of persistent clinical EAE, and propagators of inflammation within the CNS.     

Precommitment of CD4+CD8+ thymocytes to either CD4 or CD8 lineages.

CD4+ and CD8+ mature T cells arise from CD4+CD8+ precursors in the thymus. During this process, cells expressing T-cell receptors (TCRs) reactive with self major histocompatibility complex (MHC) class I or II molecules are positively selected to the CD8 or CD4 lineage, respectively. It is controversial whether lineage commitment of CD4+CD8+ thymocytes is controlled directly by TCR specificity for MHC (instructional model) or, alternatively, by processes that operate independently of TCR specificity (stochastic model). We show here that CD4+CD8+ thymocytes bearing a MHC class I-restricted transgenic TCR can be subject to two alternative developmental fates. One population of CD4+CD8+ cells is positively selected by MHC class I molecules to the CD8 lineage as expected, whereas the other CD4+CD8+ population rearranges endogenous TCR genes and is positively selected by MHC class II molecules to the CD4 lineage. Blocking TCR-MHC class II interactions in vivo does not interfere with the generation of CD4+CD8+ cells expressing endogenous TCRs but does prevent their subsequent maturation to CD4+ cells. These data support a version of the stochastic model in which CD4+CD8+ thymocytes are precommitted to the CD4 or CD8 lineage independently of TCR specificity for MHC and prior to positive selection.     

CD25+CD4+ T cells contribute to the control of memory CD8+ T cells

Previously we demonstrated that IL-15 and IL-2 control the number of memory CD8+ T cells in mice. IL-15 induces, and IL-2 suppresses the division of these cells. Here we show that CD25+CD4+ regulatory T cells play an important role in the IL-2-mediated control of memory phenotype CD8+ T cell number. In animals, the numbers of CD25+CD4+ T cells were inversely correlated with the numbers of memory phenotype CD8+ T cells with age. Treatment with anti-IL-2 caused CD25+CD4+ T cells to disappear and, concurrently, increased the numbers of memory phenotype CD8+ T cells. This increase in the numbers of CD8+ memory phenotype T cells was not manifest in animals lacking CD4+ cells. Importantly, adoptive transfer of CD25+CD4+ T cells significantly reduced division of memory phenotype CD8+ T cells. Thus, we conclude that CD25+CD4+ T cells are involved in the IL-2-mediated inhibition of memory CD8+ T cell division and that IL-2 controls memory phenotype CD8+ T cell numbers at least in part through maintenance of the CD25+CD4+ T cell population.