卵巢癌患者一线化疗后CD8~+T细胞和NK细胞数量及功能动态变化的研究

目的:研究晚期卵巢癌患者经一线化疗后体内CD8+T细胞和NK细胞数量及功能的动态变化.方法:选取术后行紫杉醇联合卡铂化疗的晚期卵巢上皮癌患者共13例,采集化疗前(S_0)、化疗后5-7天(S_1)、化疗后12～14天(S_2)和化疗后25～28天(S_3)外周血,流式细胞术检测患者外周血中CD3~+、CD4~+、CD8~+和NK细胞的百分比及绝对数量.采用体外自体肿瘤细胞裂解物脉冲淋巴细胞共培养的方法检测不同时间点CD8~+T细胞IFN-γ的分泌功能,并以LDH释放法测定NK细胞对K562细胞的杀伤活性.结果:在一个完整的化疗周期中,CD3~+、CD4~+、CD8~+细胞的绝对数目均于S_1期降至最低点,且与S_0期分别都有显著性差异.与对照组相比,当体外给予自身肿瘤细胞裂解物刺激诱导培养后,在S_1、S_2和S_3期产生IFN-γ的CD8~+细胞比例均较对照组显著增加,且CD8~+IFN-γ~+细胞比例在S2期达到最高.NK细胞的绝对数目于S1期降至最低点,且与S0期有显著性差异,NK细胞的比例及杀伤活性在化疗前、后均无显著性差异.结论:卵巢癌患者于一线化疗后机体经历免疫重建的过程,该过程中CD8~+T细胞介导的免疫应答一过性增高,而NK细胞的杀伤活性无明显变化.化疗后免疫重建期可能是免疫治疗实施的最佳窗口期.     

卵巢癌患者一线化疗后Tc1/Tc2亚群漂移及免疫应答功能动态变化的研究

目的 研究晚期卵巢癌患者经一线化疗后体内Tc1/Tc2免疫细胞亚群漂移及免疫应答功能的动态变化,以期明确化疗后机体是否存在抗肿瘤免疫抑制暂时逆转的"窗口期".方法 选取术后行紫杉醇联合卡铂化疗的晚期卵巢上皮癌患者共13例为患者组,健康女性13例作为对照组.采集化疗前(S_0)、化疗后5～7 d(S_1)、化疗后12～14 d(S_2)和化疗后25～28 d(S_3)外周血,流式细胞术检测患者外周血中Tc1/Tc2免疫细胞亚群的动态变化,同时采用体外自体肿瘤细胞裂解物脉冲淋巴细胞共培养的方法检测不同时间点CD8~+细胞IFN-γ的分泌功能.结果 晚期卵巢癌患者化疗前Tc1比例、Tc1/Te2细胞比值较对照组显著降低,而Tc2比例则显著升高.化疗后Tc1细胞比例在S_2期较S_0期显著增高,Tc2细胞比例在化疗后无显著变化,Tc1/Tc2细胞比值在S_2期显著增高.当体外给予自身肿瘤细胞裂解物刺激诱导培养后,分泌IFN-γ的CD8~+细胞比例在S_2期达到最高.结论 卵巢癌患者于一线化疗后机体Tc1/Tc2亚群动态漂移,其细胞比值在S_2期显著升高;S_2期亦是CD8~+细胞免疫应答达到最高峰的时间点.化疗有可能通过机体免疫重建诱生了增强的抗肿瘤免疫应答,从而使机体抗肿瘤免疫抑制得到暂时逆转.免疫重建期可能是免疫治疗实施的最佳窗口期.     

CHOP方案治疗前后外周T细胞淋巴瘤患者外周血CD45RA~+ T和CD45RO~+ T的变化特点

目的:探讨CHOP方案对外周T细胞淋巴瘤(PTCL)患者外周血中初始和记忆T细胞水平的变化及其临床意义。方法:采用流式细胞术检测20例PTCL患者CHOP方案化疗前后外周血中CD4+CD45RA+、CD4+CD45RO+、CD8+CD45RA+和CD8+CD45RO+T细胞的比例,分析疗效与T细胞亚群的关系。结果:PTCL患者化疗前外周血中CD4+T细胞、CD4+CD45RO+细胞的比例明显降低,CD4+CD45RA+、CD8+、CD8+CD45RO+和CD8+CD45RA+T细胞的比例均明显升高(P<0.05),而化疗后PTCL患者CD4+、CD4+CD45RO+细胞的比例较治疗前升高,CD4+CD45RA+、CD8+、CD8+CD45RO+和CD8+CD45RA+T细胞比例则较治疗前稍下降(P<0.05)。治疗前后化疗有效组的CD4+CD45RA+均明显高于化疗无效组(P<0.05)。结论:CHOP治疗对PTCL患者胸腺输出功能有一定的影响,伴有较高胸腺输出功能者对化疗效果更好。     

丙种球蛋白输注对川崎病患儿外周血CD4~+CD25~+调节T细胞与淋巴细胞亚群分布的影响

目的探讨丙种球蛋白输注对川崎病患儿外周血CD4~+CD25~+调节T细胞(Treg)与淋巴细胞亚群分布的影响及临床意义。方法流式细胞术检测40例川崎病患儿和30例体检健康儿童外周血中CD4~+CD25~+Treg细胞的表达水平以及108例川崎病患儿和41例体检健康儿童外周血中淋巴细胞亚群分布。ELISA法检测川崎病患儿血浆中TGF-β1浓度。108例川崎病患儿中有30例收集到对应的丙种球蛋白(IVIG)治疗后全血,流式细胞术检测CD4~+CD25~+Treg、TGF-β1及淋巴细胞亚群在川崎病患儿丙种球蛋白(IVIG)治疗前后表达水平的差异。结果与健康体检组相比,川崎病患儿CD4~+CD25~+Treg细胞及血浆TGF-β1的表达水平明显降低,外周血CD3+、CD8~+T细胞及NK细胞的表达水平明显降低,CD4~+T细胞、B细胞及CD4~+/CD8~+水平明显增高,差异均有统计学意义(均P0.01)。与IVIG治疗前相比,川崎病患儿IVIG治疗后外周血CD4~+CD25~+Treg细胞及血浆TGF-β1的表达水平明显增高(均P0.05),外周血CD3+、CD8~+T细胞及NK细胞的表达水平明显增高(均P0.05),CD4~+T细胞、B细胞及CD4~+/CD8~+水平明显降低(均P0.05)。治疗后患儿外周血CD4~+CD25~+Treg水平、血浆TGF-β1浓度及淋巴细胞亚群表达水平与健康对照相比无差异(P0.05)。结论 Treg细胞与淋巴细胞比例失常是导致儿童川崎病免疫紊乱的重要原因。检测CD4~+CD25~+调节T细胞及淋巴细胞亚群分布对评估川崎病患儿的细胞免疫状况,辅助诊断和指导治疗具有重要的临床价值。     

大肠癌患者与正常健康人淋巴细胞表型差异分析

目的:分析大肠癌患者与正常健康人20项淋巴细胞亚群变化情况。方法:流式细胞术(FCM)检测168例大肠癌患者与102例正常健康人外周血20项淋巴细胞亚群,SPSS17.0软件进行统计学处理。结果:与正常健康人相比,大肠癌患者CD29+、45RA+、CD4+CD45RO+和CD8+CD28-细胞百分比例明显升高,而NKT、45RO+、CD4+CD45RA+、CD28+和CD8+CD28+细胞百分比例则明显降低(P<0.05)。Ⅳ期患者组CD8+CD28-细胞百分比例明显高于正常健康人组、Ⅰ+Ⅱ期患者组及Ⅲ期患者组(P<0.05)。结论:大肠癌患者的细胞免疫功能降低,体液免疫功能有所增强;传统指标难以准确评价患者的免疫功能,包括CD8+CD28+、CD8+CD28-在内的多项细胞亚群分析体系也许能更好的反映大肠癌患者的免疫状况。     

红景天乙醇提取物调节Lewis肺癌荷瘤小鼠肿瘤浸润T细胞数量并增强抗肿瘤免疫效应

目的探讨藏药红景天(RRL)的抗肿瘤免疫功能。方法将Lewis肺癌荷瘤小鼠随机分为生理盐水组、 500 mg/kg RRL乙醇提取物处理组和10 mg/kg环磷酰胺(CTX)处理组,处理10 d。计算小鼠生存率和肿瘤生长抑制率;流式细胞术检测肿瘤浸润的CD4~+T、 CD8~+ T细胞数量及FOXP3~+调节性T细胞(Treg)占CD4~+CD25~+Treg的比例; ELISA检测荷瘤小鼠血清中白细胞介素2 (IL-2)和γ干扰素(IFN-γ)水平,乳酸脱氢酶(LDH)释放法检测脾细胞毒性T淋巴细胞(CTL)活性。结果 RRL乙醇提取物处理的Lewis荷瘤小鼠生存率显著提高,肿瘤生长受到抑制,肿瘤浸润的CD4~+T细胞和CD8~+T细胞数量增加, FOXP3~+ Treg占CD4~+CD25~+Treg的比例降低。荷瘤小鼠血清IFN-γ和IL-2水平提高,脾脏CTL的杀伤能力增强。结论 RRL乙醇提取物通过调节免疫细胞数量和功能增强抗肿瘤免疫效果。     

转录因子HELIOS在系统性红斑狼疮患者外周血调节性T细胞亚群中表达格局分析

Treg细胞在系统性红斑狼疮(SLE)发生发展中具有重要作用,而转录因子HELIOS在Treg细胞发挥免疫抑制功能方面发挥关键作用。本研究应用流式细胞术分析HELIOS在SLE患者外周血中CD4~+Treg细胞亚群中的表达格局,有助于揭示SLE的发病机制。结果显示,与健康对照相比,SLE患者外周血CD4~+T细胞中CD25~+Foxp3~+Treg细胞比例显著下降;在CD4~+CD25~+T细胞中,表型为CD39-CD45RA~+Treg细胞(幼稚型Treg细胞)比例显著升高,表型为CD39~+CD45RA-Treg细胞(效应型Treg细胞)比例显著下降,而表型为CD39-CD45RA-T细胞(非Treg细胞)比例不变;在Treg细胞中发挥重要免疫调节作用的转录因子HELIOS,在幼稚型Treg和效应型Treg细胞中比例均显著下降,提示CD4~+Treg细胞亚群比例失衡及其HELIOS表达下调可能在SLE发病机制中发挥重要作用。     

子宫内膜异位症患者外周血CD4~+CD25~+Foxp3~+调节性T细胞的变化

观察子宫内膜异位症患者外周血单个核细胞CD4~+CD25~+Foxp3~+调节性T细胞的数量变化,初步探讨其意义。采用流式细胞术检测20例健康对照者(对照组)及46例子宫内膜异位症患者(疾病组临床r-AFS分期:Ⅰ～Ⅱ期26例,Ⅲ～Ⅳ期20例)外周血单个核细胞(PBMC)中CD4~+CD25~+Foxp3~+调节性T细胞数目,并计算CD4~+CD25~+Foxp3~+调节性T细胞占CD4~+T淋巴细胞的百分率;分析不同分期子宫内膜异位症患者外周血CD4~+CD25~+Foxp3~+调节性T细胞的变化。结果显示,与健康对照组相比,疾病组PBMC中CD4~+CD25~+Foxp3~+Treg占CD4~+T淋巴细胞的百分率及CD4~+CD25~+Foxp3~+Treg绝对数均明显升高(P<0.01,P<0.05);疾病组中,Ⅲ～Ⅳ期的PBMC中CD4~+CD25~+Foxp3~+Treg占CD4~+T淋巴细胞的百分比及CD4~+CD25~+Foxp3~+Treg绝对值较Ⅰ～Ⅱ期均明显升高(P<0.01,P<0.05)。提示子宫内膜异位症患者外周血CD4~+CD25~+Foxp3~+调节性T细胞数目和比例增多,可能存在自身免疫调节功能的紊乱,且与病程发展紧密相关。     

DC-CIK免疫治疗联合化疗对多发性骨髓瘤患者外周血T细胞亚群及Treg细胞的影响

为研究树突状细胞和细胞因子诱导的杀伤细胞(CIK)为效应细胞的过继免疫联合化疗治疗多发性骨髓瘤(MM)的临床疗效及对患者外周血T细胞亚群、CD4+CD25+调节性T(Treg)细胞的影响,探讨以上治疗对MM患者的细胞免疫调节功能。将36例MM患者随机分为两组:化疗组18例,给予合适的化疗方案;联合组18例,除接受适合的化疗外,还给予DC/CIK免疫治疗,比较两组患者的临床疗效及外周血T细胞亚群、CD4+CD25+调节性T(Treg)细胞比例。结果显示,3周期治疗后,联合组患者的生活质量和临床疗效均比化疗组患者显著提高(P<0.05)。联合组CD3+CD8+比例、CD4+CD25+/CD4+、CD4+CD25+FoxP3+/CD4+CD25+比值均明显低于化疗组(P<0.05);CD3+CD4+/CD3+CD8+比值明显高于化疗组(P<0.05),提示联合治疗组对MM具有更有效的免疫调节功能。研究结果表明DC/CIK免疫治疗联合化疗治疗MM有良好的临床疗效和应用价值,可能是通过免疫调节使MM患者Th2向Th1逆转,从而增强机体抗肿瘤效应的。     

不同化疗方案治疗T细胞淋巴瘤的疗效比较

目的 探讨不同化疗方案治疗外周T淋巴细胞瘤(peripheral t-cell lymphoma,PTCL)的疗效.方法 将2010年8月至2015年1月医院收治的初诊PTCL患者40例,根据用药方案分为2组,CHOP(环磷酰胺+表柔比星+长春新碱+泼尼松)/CHOP样方案作为CC组24例,Hyper CVAD(大剂量环磷酰胺、表柔比星、长春新碱、地塞米松)/MA(大剂量甲氨蝶呤、阿糖胞苷)方案作为HM组16例,记录近期疗效、生存情况、化疗毒副反应,比较化疗前后T淋巴细胞亚群、CD4+和CD8+T细胞中CD45RA+、CD45RO+T细胞分布情况.结果 HM组缓解率为87.5%高于CC组的54.17%(P<0.05),两组Ⅰ~Ⅱ期化疗缓解率高于Ⅲ~Ⅳ期.两组化疗后CD4+、CD4+/CD8+、CD4+CD45RO+均较治疗前升高,且HM组升高幅度较CC组明显(P<0.05);化疗后CD8+、CD4+CD45RA+、CD8+CD45RA+、CD8+CD45RO+较治疗前下降(P<0.05),其中HM组CD8+、CD4+CD45RA+、CD4+CD45RO+下降幅度较CC组明显.HM组中位无进展生存期为25个月长于CC组的12个月(P<0.05),1年无进展生存期几率为81.25%高于CC组的45.83%(P<0.05);两组2年、3年无进展生存期及1年、2年、3年总生存期比较差异无统计学意义(P>0.05).HM组中性粒细胞减少、血小板减少发生率分别为68.75%、62.5%高于CC组的20.83%、16.67%(P<0.05).结论 Hyper CVAD/MA治疗初诊PTCL近期疗效好,可延长中位PFS,调节机体免疫功能,但中性粒细胞减少、血小板减少发生率较高,应给予高度重视.     

The significance of Treg cells in defective tumor immunity

Regulatory T cells (Treg) enriched in FoxP3+, glucocorticoid-induced TNF receptor+, and cytotoxic T-lymphocyte-associated antigen-4+ exert a potential to suppress effector T cells in the periphery. These cells exist in markedly higher proportions within tumor-infiltrating lymphocytes, peripheral blood lymphocytes, and/or regional lymph node lymphocytes of patients with cancer and their frequencies are suggested to be strongly related to tumor progression and inversely correlated with the efficacy of treatment. Tumor-specific Treg cells require ligand-specific activation and cell-to-cell contact to exert their suppressive activity on tumor-specific effector cells (CD8+ cytotoxic T lymphocytes and CD4+ Th cells), which includes decreased cytotoxity, proliferation, and Th1 cytokine secrection. Depletion or blockade of Treg cells can enhance immune protection from tumor-associated antigens that are expressed as self antigens. Recent studies revealed that lymphoma T cells might adopt a Treg profile as well. Studies assessing the influence of chemotherapy on Treg cells have also been included in this review.     

肺癌患者CD4+CD25high Foxp3+调节性T细胞的格局变化及意义

目的：研究肺癌患者外周血（PBMC）及肿瘤浸润淋巴细胞（TIL）中CD4^＋ CD25^high Foxp3^＋调节性T细胞（Treg）的比例改变，探讨其在抗肿瘤免疫中的调节作用。方法：分离肺癌患者PBMC及TIL，FACS分析CD4^＋／CD8^＋T细胞的比值及CD4^＋ CD25^highT细胞占CD4^＋T细胞的比例。Real-time PCR检测Treg特异性转录因子Foxp3基因在PBMC及TIL中的表达。结果：肺癌患者PBMC及TIL中CD4^＋／CD8^＋比值降低；而CD4^＋ CD25^high T细胞在CD4^＋T细胞中所占比例升高；Foxp3基因仅在TIL中高表达，而在PBMC中低或不表达，表明肿瘤局部的CD4^＋ CD25^high T细胞主要是CD4^＋ CD25^high Foxp3^＋ Treg。结合临床资料分析显示Treg在肺腺癌比例较高。结论：CD4^＋ CD25^high Foxp3^＋ Treg在肺癌患者肿瘤浸润淋巴细胞中明显升高，可能与其通过细胞与细胞间接触抑制CD8^＋T细胞的杀伤效应，最终发挥免疫抑制效应相关。     

新辅助化疗对局部进展期乳腺癌患者T淋巴细胞亚群及NK细胞免疫功能的影响

目的:探讨局部进展期乳腺癌患者新辅助化疗前、后T淋巴细胞亚群及NK细胞免疫功能的变化。方法:采用流式细胞术检测54例局部进展期乳腺癌患者新辅助化疗前后的静脉血T淋巴细胞亚群及NK细胞免疫功能。美国癌症联合会(American Joint Commitree on Cancer,AJCC)肿瘤分期为Ⅱb期(仅T3N0M0)和Ⅲ期(不包括N3),静脉血于第1周期新辅助化疗治疗前及第3周期化疗后21日抽取,淋巴细胞亚群检测包括:T(CD3+,CD4+,CD8+),NK(CD56+,CD16+),经过3周期新辅助化疗CEF方案(表柔比星、环磷酰胺和5-氟尿嘧啶),根据新辅助化疗临床效果评价分为2组,化疗有效组38例(CR和PR),化疗无效组16例(SD和PD),并与正常体检健康者(40例)作比较。结果:乳腺癌患者治疗前CD4+、CD4+/CD8+明显低于对照组(P<0.01),NK细胞明显低于对照组(P<0.05),新辅助化疗后,有效组总CD3+、CD4+、CD4+/CD8+、NK细胞较治疗前均显著升高(P<0.05),CD8+降低(P<0.05);无效组CD3+、CD4+/CD8+及NK细胞较治疗前显著降低(P<0.05),而CD8+升高(P<0.05)。结论:局部进展期乳腺癌患者免疫功能低下,有效的辅助化疗能提高患者的免疫功能,定期监测免疫功能对指导临床治疗有意义。     

流式细胞术检测调节性T细胞方法的建立

目的建立流式细胞术（FCM）检测外周血CD4＋CD25＋调节性T细胞（Tregs）的方法，并观察紫杉醇联合卡铂治疗对晚期肺癌和乳腺癌患者外周血CD4＋CD25＋Tregs数量的影响。 方法19例晚期肺癌和10例乳腺癌患者均给予紫杉醇联合卡铂方案化疗，于化疗前1d和化疗后第7天采集患者外周血，分别加入鼠抗人CD4-FITC（异硫氰酸荧光素）/CD8-PE（藻红蛋白）/CD3-PerCP（多甲藻叶绿素蛋白）、CD25-FITC/CD127-PE/CD4-PerCP、CD3-FITC/CD（16＋56）-PE/CD45-PerCP单抗，并以分别加入同型鼠抗人IgG1-FITC、IgG1-PE、IgG1-PerCP抗体作为阴性对照。采用流式细胞术（FCM）检测化疗前后外周血CD3＋、CD4＋、CD8＋T细胞和CD4＋CD25＋Tregs、NK细胞所占比例并进行数据分析。实验重复3次。 结果与化疗前比较，晚期肺癌和乳腺癌患者化疗后外周血CD4＋CD25＋Tregs的比例均明显降低（6.82%±3.11%vs.5.48%±2.13%，P=0.045；6.38%±1.84%vs.3.88%±1.69%，P=0.007）；晚期肺癌患者化疗后外周血CD4＋T细胞的比例升高（48.84%±16.44%vs.56.35%±14.50%，P=0.006），CD8＋T细胞的比例降低（51.18%±16.44%vs.43.65%±14.50%，P=0.006），CD4＋/CD8＋T细胞比值升高（1.12±0.60vs.1.57±0.88，P=0.008），而CD3＋T细胞和NK细胞的比例均无明显变化；乳腺癌患者化疗后外周血CD3＋、CD4＋、CD8＋T细胞、NK细胞的比例和CD4＋/CD8＋T细胞比值均无明显变化。 结论成功建立了FCM检测CD4＋CD25＋Tregs的方法，联合应用CD4、CD25、CD127检测CD4＋CD25＋Tregs简便可行、重复性好，检测结果可靠、准确，比较适用于临床检验。紫杉醇联合卡铂能够降低晚期肺癌和乳腺癌患者外周血CD4＋CD25＋Tregs的数量。     

Recent thymic emigrants and subsets of naive and memory T cells in the circulation of patients with head and neck cancer

Apoptosis of circulating CD8+ T lymphocytes is a frequent finding in patients with cancer. T-cell output by the thymus or antigen-driven expansion of circulating T cells could compensate for apoptosis and thus normalize their homeostasis. We studied the frequency of recent thymic emigrants (RTE) identified by T-cell receptor excision circles (TREC) and of naive and memory T-cell subsets in peripheral blood samples obtained from 39 patients with head and neck cancer (HNC) and 33 age-matched controls (NC). TREC numbers were determined by real-time quantitative PCR, and CD8+CD45RO-CD27+ or CD4+CD45RO-CD27+ T-cell subsets were quantified by flow cytometry. Age-associated decreases in TREC numbers and proportions of naive CD8+ and CD4+ T-cell subsets were significantly greater in cancer patients than NC. In contrast, the memory compartment was expanded, with increased proportions of CD4+CD45RO+ but not CD8+CD45RO+ T cells, in cancer patients vs. NC. These alterations did not normalize in patients who were NED. The data suggest that lower thymic output combined with rapid turnover of naive CD8+ T cells account for altered lymphocyte homeostasis in HNC patients. The defect persists long after curative treatments and may contribute to immune cell dysregulation in patients with cancer.     

T regulatory cells in atopic dermatitis and subversion of their activity by superantigens

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease involving colonization by superantigen (SAg)-secreting Staphylococcus aureus. CD4+CD25+ T regulatory (Treg) cells are thought to play an important role in controlling inflammatory responses. OBJECTIVE: In this study we examined whether Treg cells might be deficient in patients with AD. METHODS: CD4+CD25+ and CD4+CD25- T cells were isolated from PBMCs by using immunomagnetic beads. Cells were cultured with anti-CD3 or SAg, staphylococcal enterotoxin B (SEB), for 72 hours. Proliferation was measured by means of tritiated thymidine incorporation. CD4, CD8, CD25, and cutaneous lymphocyte-associated antigen expression on PBMCs was assessed by means of flow cytometry. RNA was extracted from isolated subsets of T cells, and the results of real-time PCR for FoxP3 mRNA were determined. RESULTS: Surprisingly, CD4+CD25+ T cells were significantly (P <.01) increased in patients with AD (6.68%+/-0.99%, n=15) compared with in asthmatic patients (3.42%+/-0.58%, n=12) or nonatopic healthy control subjects (3.34%+/-0.43%, n=14). Patients with AD also had a higher expression of CD25+ in skin-homing, CD4+, cutaneous lymphocyte-associated antigen-positive T cells than asthmatic and nonatopic subjects, with values of 35.95% versus 22.44% versus 23.03%, respectively (P <.006). Only CD4+CD25+ cells expressed FoxP3, whereas CD4+CD25- T cells and CD4- cells did not. Consistent with known properties of Treg cells, CD4+CD25+ cells were anergic to anti-CD3 stimulation. When CD4+CD25+ cells from each study group were mixed with CD4+CD25- cells, proliferative responses were equally suppressed after anti-CD3 stimulation. In contrast, after SEB stimulation, CD4+CD25+ cells were no longer anergic. Furthermore, when CD4+CD25+ cells were mixed with CD4+CD25- cells and stimulated with SEB, the suppressive function of Treg cells was reversed. CONCLUSION: Patients with AD have significantly increased numbers of peripheral blood Treg cells with normal immunosuppressive activity. However, after SAg stimulation, Treg cells lose their immunosuppressive activity. These data suggest a novel mechanism by which SAgs could augment T-cell activation in patients with AD.     

Recent thymic origin, differentiation, and turnover of regulatory T cells

Regulatory CD4+ T cells (Treg) are essential to maintain self-tolerance. Release of natural Treg from the thymus is believed to commence soon after birth, but it is unclear how many are produced by "conversion" in the periphery, whether numbers are maintained after puberty by general homeostatic mechanisms that regulate lymphocyte numbers, or whether significant numbers are produced by the involuted thymus. To address the origin of Treg in normal adult rats, we focused on recent thymus emigrants (RTE). Approximately 30% of CD4+CD25+forkhead box p3 (Foxp3)+ Treg expressed markers associated with RTE. Following thymectomy, numbers of cells expressing these markers fell by 80% within 30 days. Furthermore, although only approximately 5% of CD4+ single-positive thymocytes expressed Foxp3 within 24 h after intrathymic injection of FITC, more than 30% of the labeled CD4+ RTE were Foxp3+, suggesting that some RTE may acquire Foxp3 in the periphery. Thus, some RTE may acquire Foxp3 rapidly after emigration from the thymus. Treg are dividing rapidly with apparent half-lives of approximately 18 days and approximately 7 days for the CD4+CD25+Foxp3+ and CD4+CD25-Foxp3+ subsets, respectively. The apparently slower turnover of CD4+CD25+Foxp3+ cells is a result of CD4+CD25+Foxp3+ --> CD4+CD25-Foxp3+ conversion, with no loss of regulatory function. Taken together, the data suggest that Treg in adults are relatively short-lived and that their numbers are maintained by rapid cell division and continuous replenishment from the thymus.