CD28/CTLA-4:B7在特发性血小板减少性紫癜患者外周血淋巴细胞中的表达及意义

目的:探讨特发性血小板减少性紫癜(ITP)患者外周血淋巴细胞CD28、CTLA-4(CD152)、B7-1(CD80)及B7-2(CD86)的表达及意义。方法:采用免疫荧光标记和流式细胞术检测41例ITP患者和40例健康对照者外周血CD3+CD28+细胞、CD3+CD152+细胞、CD80+CD19+细胞和CD86+CD19+细胞分别占淋巴细胞的比例及血小板表面相关抗体水平,进行2组对比、分析。结果:与正常对照组相比,急性ITP患者外周血CD3+CD28+细胞和CD3+CD152+细胞差异无统计学意义(P0.05),CD80+CD19+细胞增多(P0.05),CD86+CD19+细胞显著增多(P0.01),慢性ITP患者CD86+CD19+细胞增多(P0.05);急性ITP患者外周血CD86+CD19+细胞较慢性ITP患者增多(P0.05);与正常对照组相比,急性ITP患者PAIg's、PAIgG和PAIgM水平显著增高,慢性ITP患者PAIgG水平增高;CD80、CD86表达与PAIgG水平之间存在显著的相关性(均P0.01)。结论:ITP患者外周血B淋巴细胞上CD86和CD80表达均异常,可能与其发病相关。     

强直性脊柱炎患者外周血CD28 CD40共刺激通路相关分子的表达

目的探讨强直性脊柱炎(AS)患者外周血淋巴细胞CD28和CD40共刺激通路相关分子的表达及其与免疫功能紊乱的关系。方法采用流式细胞仪检测69例AS初诊患者和50名健康对照者CD28、CTLA-4和CD40L在外周血CD3~ T细胞上的表达及CD80、CD86和CD40在CD19~ B细胞上的表达。用ELISA法测定血清中免疫球蛋白IgG、IgA和IgM的水平。结果AS患者CD3~ T细胞上的CD28、CTLA-4和CD40L,CD19~ B细胞上CD86和CD40的表达均较正常对照组显著增高(P＜0．01),CD80在CD19 B细胞表达增高(P＜0．05)：AS患者血清中2种免疫球蛋白IgG、IgA的水平较正常对照组显著增高(P＜0．01)。结论AS患者CD28和CD40共刺激通路相关分子表达增强,机体处于免疫激活状态,CD28和CD40共刺激通路在AS的发病中可能起重要作用。     

共刺激分子CD28/CTLA-4-B7与1型糖尿病

CD2 8/细胞毒性T淋巴细胞相关抗原 (CTLA) 4与B7的相互作用是T细胞活化的重要调节因子 ,在自身免疫性疾病的发生、发展中起着不同的作用。其中 ,CD2 8 B7的过度表达是自身免疫性 1型糖尿病发生的重要原因之一 ;而CTLA4可使CD2 8 B7共刺激信号中止 ,是T淋巴细胞活化的负性调节信号。因此 ,运用B7单克隆抗体阻断CD2 8 B7通路或通过加强B7 CTLA 4作用来抑制自身免疫活性T细胞 ,有可能成为治疗该病的新手段。     

急性脑梗死患者外周血CD4CD25 T细胞和CD4CD28~- T细胞的变化

目的探讨急性脑梗死患者外周血CD4CD25T细胞和CD4CD28-T细胞亚群的变化及意义。方法选择急性脑梗死患者22例(脑梗死组),另选取健康体检者18例(对照组);均采用流式细胞仪检测外周血CD4CD25T细胞和CD4CD28-T细胞占CD4T细胞比例。结果脑梗死组外周血CD4CD25T细胞/CD4T细胞比例明显低于对照组[(41.14±9.92)%vs(49.01±12.19)%,P<0.05],而CD4CD28-T细胞/CD4T细胞比例明显高于对照组[(19.93±15.60)%vs(11.96±8.60)%,P<0.05]。结论急性脑梗死患者外周血CD4CD25T细胞比例减少,而CD4CD28-T细胞升高,两者共同作用,可能在脑梗死发生、发展中起重要作用。调节T淋巴细胞亚群可能是脑梗死的潜在治疗靶点。     

慢性乙型肝炎患者外周血CD8+CD28+T淋巴细胞百分比的变化及其临床意义探讨

目的 探讨不同病程阶段的慢性乙型肝炎患者外周血CD8⁺CD28⁺T淋巴细胞百分比的变化,以及CD8⁺CD28⁺T淋巴细胞百分比变化与血清HBsAg水平的关系。方法 2018年4月~2018年8月我院诊治的慢性乙型肝炎患者88例,其中免疫耐受期20例,免疫清除期28例,非活动期20例,再活动期20例,另选择健康人20例。使用流式细胞术检测外周血CD8⁺CD28⁺T淋巴细胞百分比。结果 健康人与免疫耐受期患者外周血CD8⁺CD28⁺T淋巴细胞百分比分别为（26.1±3.5）%和（26.3±3.4）%,差异无统计学意义（P>0.05）;免疫清除期患者CD8⁺CD28⁺T淋巴细胞百分比为（40.1±4.7）%,显著高于健康人（P<0.05）;非活动期和再活动期患者外周血CD8⁺CD28⁺T淋巴细胞百分比分别为（20.3±2.2）%和（26.1±2.2）%,显著低于健康人（P<0.05）;外周血HBsAg低、中、高三组人群外周血CD8⁺CD28⁺T淋巴细胞百分比分别为（24.0±7.5）%、（28.4±8.9）%和（33.2±8.5）%,各组间差异有统计学意义（P<0.05）。结论 不同病程阶段的慢性乙型肝炎患者外周血CD8⁺CD28⁺T淋巴细胞百分比存在明显差异,可能与病毒长期刺激机体免疫系统,导致免疫系统功能失调有关,而这种失调可能参与了慢性乙型肝炎的发病过程。     

冠状动脉粥样硬化性心脏病患者外周血共刺激分子CTLA-4、CD28的表达

目的探讨冠状动脉(冠脉)粥样硬化性心脏病(coronary heart disease,CHD)患者外周血细胞毒性T淋巴细胞相关抗原-4(cytotoxic T lymphocyte associated antigen-4,CTLA-4)、分化抗原簇28(cluster of differentiation 28,CD28)及淀粉样蛋白A(serum amyloid A protein,SAA)的表达。方法选择2017年7月至2018年6月南京医科大学康达学院第一附属医院CHD患者43例为研究对象,其中稳定型心绞痛患者21例,急性冠脉综合征患者22例。另外,选择同期20例经冠脉造影证实的非CHD患者为正常对照组。患者在起病入科时抽取外周血,CTLA-4、CD28及SAA的浓度采用酶联免疫吸附法(enzyme-linked immunoassay,ELISA)检测。结果与正常对照组比较,稳定型心绞痛组、急性冠脉综合征组患者外周血CTLA-4浓度降低,SAA、CD28浓度升高且急性冠脉综合征组浓度升高更高,差异有统计学意义(P0.05);急性冠脉综合征组SAA与CD28呈正相关(r=0.871,P0.01),与CTLA-4呈负相关(r=-0.642,P0.01)。结论 CHD患者外周血CTLA-4浓度降低,CD28浓度升高,急性冠脉综合征患者更甚,且其与常规的SAA检测指标呈相关性,可用于评估病情的严重程度并作为CHD治疗的新靶点。     

CTLA-4及其衍生物和支气管哮喘

在过敏性哮喘的发病机制中,Th1/Th2亚群数目和（或）功能比例失衡是哮喘最重要的免疫学异常,其中CD4^＋T细胞在启动抗原特异性免疫应答过程中起重要作用,它的增殖活化需要两个刺激信号：第一信号（识别信号）由T细胞受体（TCR）与抗原提呈细胞（APC）提呈的MHC-抗原肽复合物相结合所产生,第二信号（共刺激信号）由APC表面的共刺激分子与T细胞表面对应受体分子相结合产生.目前认为CD28和CTLA-4是一对具有正负调节功能的重要共刺激分子,细胞毒性T细胞相关性抗原-4（CTLA-4）和CD28竞争性结合B7分子从而下调或终止T细胞反应.CTLA4-Ig能有效抑制哮喘动物模型的气道高反应性、肺部嗜酸粒细胞（EOS）增多等表现,使抗原导致的气道功能紊乱症状明显减轻.但研究表明,T细胞的活化存在非CD28依赖的途径,而且CTLA4-Ig阻断CD28/B7共刺激途径诱导的T细胞无能在一定条件下可以逆转,因此,CTLA4-Ig的单独使用价值有一定的局限性.CTLA4-FasL融合蛋白在体外能抑制混合淋巴细胞反应和诱导淋巴细胞凋亡效应,且作用比CTLA4-Ig和sFasL联合应用强.设想CTLA-4及其衍生物将为哮喘临床治疗提供广阔前景.本文就该问题作一综述.     

CD4＋CD28-T淋巴细胞在急性冠状动脉综合征中的表达及临床意义

研究表明动脉粥样硬化是一种慢性免疫炎症性疾病。目前与T淋巴细胞相关的免疫细胞及免疫分子在冠心病发生发展中的作用已成为研究热点,近年来在急性冠状动脉综合征患者动脉粥样斑块和外周血中发现了一种不同寻常的T细胞——CD4＋CD28-T细胞,并发现CD4＋CD28-T淋巴细胞在急性冠状动脉综合征中可持续存在,且与预后有关,同时可能成为急性冠状动脉综合征治疗的新的靶点。     

慢性肝病患者外周血T细胞CD28表达与中医分型关系的探讨

目的：探讨慢性乙型肝炎和肝硬化患者外周血T细胞亚群(即CD8^ 、CD4^ 细胞)CD28分子的表达与中医辨证分型的相互关系。方法：对门诊和住院的慢性乙型肝炎和肝硬化活动期患者82例、正常对照人群20例的外周血T淋巴细胞亚群CD28分子表达测定，结合中医辨证分析，从免疫学角度讨论两者相互关系。结果：所观察的CD28、CD4和CD4／CD8各数据组中，将慢性乙型肝炎和肝硬化活动期的中医辨证分型各组之值与正常对照组进行比较，经统计学处理，P＞0．05；分型的各组总体差异，P＜0.05或P＜0．01；分型各组组间比较，P＜0．05或P＜0．01。慢性乙型肝炎、肝硬化中医分型各组的CD28表达水平与正常对照组相比，有显著差异；中医分型各组间亦有一定差异。从CD28^ CD8^ 看，湿热中阻型明显升高，而其他3组与正常组相似；从CD28^ CD4^ 看，肝郁脾虚型与湿热中阻型与正常组虽无明显差异，但其应答强弱顺序颇能说明问题，即肝肾阴虚组＞肝郁脾虚和温热中阻组＞瘀血阻络组。结论：CD28表达可在慢性肝病中医辨证分型中发挥一定作用。     

胰岛素抵抗的慢性丙型肝炎患者外周血CD4+CD25+调节性T细胞的数量及其功能

目的 了解胰岛素抵抗的慢性丙型肝炎患者外周血CD4 +CD25+调节性T细胞(Treg)数量和功能的变化.方法 筛选40例HLA-A2+慢性丙型肝炎患者(其中20例合并胰岛素抵抗),流式细胞仪检测患者CD4+CD25+Treg细胞占外周血中CD4+T细胞的频率,液闪计数仪检测对HCV特异性CD8+T细胞增殖的抑制作用,ELISA法检测IFN-y水平.统计学处理采用t检验.结果 胰岛素抵抗的慢性丙型肝炎患者外周血CD4 +CD25+ Treg细胞占CD4+T细胞的(9.5±1.9)％,明显低于慢性丙型肝炎患者的(11.2±2.2)％(t=2.615,P＜0.05).胰岛素抵抗指数(HOMA-IR)≥4患者的CD4+CD25+ Treg细胞比例为(9.0±1.8)％,明显低于HOMA-IR＜4患者的(10.8±2.3)％(t=2.413,P＜0.05).胰岛素抵抗的慢性丙型肝炎患者CD4+CD25+ Treg细胞和去除Treg的外周血单个核细胞(PBMC)共培养上清液中IFN-y为(4 050±580) pg/mL,明显高于慢性丙型肝炎患者的(2 005±330)pg/mL(t=13.705,P＜0.01).HOMA-IR≥4患者IFN-y为(5 682±986)pg/mL,明显高于HOMA-IR＜4患者的(2 819±660) pg/mL(t=7.630,P＜0.01).结论 随着胰岛素抵抗程度加重,慢性丙型肝炎患者外周血CD4+ CD25+ Treg细胞频率减低,对HCV特异性CD8+T细胞增殖的抑制作用减弱.     

老年原发性非小细胞肺癌患者外周血中CD28/CTLA-4 mRNA含量变化及临床意义

目的 探讨外周血中CD28/CTLA-4 mRNA含量的增龄性改变与老年原发性非小细胞肺癌(NSCLC)发生发展之间的联系.方法 应用实时荧光定量PCR技术对63例老年NSCLC患者外周血单个核细胞CD28/CTLA-4 mRNA的含量进行检测,结果分别与老年健康组、老年肺良性病变组(老年非癌组)、年轻健康组、年轻肺良性病变组(年轻非癌组)以及年轻肺癌组进行对比分析,同时分析它们与临床病理特征之间的关系.结果 老年肺癌组外周血中CD28 mRNA含量显著低于其余各组(P＜0.01),而CTLA-4 mRNA含量则显著高于其余各组(P＜0.01),老年健康组外周血中CD28 mRNA含量明显低于年轻健康组和年轻非癌组,而CTLA-4 mRNA含量则明显高于年轻健康组和年轻非癌组;老年非癌组与老年健康组比较,两者含量差异均无统计学意义.Logistic回归分析显示,年龄、CD28 mRNA含量、CTLA-4 mRNA含量均与肺癌的发生有统计学关联(均P＜0.01),且CD28与CTLA-4的mRNA含量具有负相关性(r=-0.400,P＜0.01).另外,CD28及CTLA-4 mRNA的含量均与老年肺癌的临床TNM分期、细胞分化程度以及淋巴结转移状态密切相关(P＜0.05,P＜0.01),而与病理类型无关(P＞0.05).结论 呈增龄性调节的CD28/CTLA-4 mRNA可能在老年人NSCLC的形成和演变过程中发挥着重要的调控作用.     

慢性丙型肝炎患者外周血单个核细胞HCV RNA检测及其与机体免疫功能的相关性研究

目的观察慢性丙型肝炎患者外周血单个核细胞(PBMC)HCVRNA含量及其对T淋巴细胞亚群的影响,以探讨HCV感染者PBMC中HCVRNA水平及其与机体免疫功能的关系。方法采用荧光定量PCR(FQPCR)技术对128例丙型肝炎患者血清、外周血单个核细胞的HCVRNA含量进行了检测,同时检测CD3+、CD4+、CD8+、CD4+/CD8+。结果PBMC内HCVRNA阳性组与HCVRNA阴性组比较,前者CD3+、CD4+水平降低、CD8+水平增高,CD4+/CD8+比值下降大于后者,差异有显著性(P<0.05)。结论丙型肝炎病毒侵染PBMC后可加重患者的细胞免疫功能紊乱。     

Dysregulation of CD28 and CTLA-4 expression by CD4 T cells from previously immunodeficient HIV-infected patients with sustained virological responses to highly active antiretroviral therapy

OBJECTIVES: Current guidelines recommend commencing highly active antiretroviral therapy (HAART) in HIV-infected patients when CD4 T-cell counts reach 350 cells/microL. However, late-presenting HIV-infected patients with CD4 T-cell counts<50 cells/microL are still common. The ability of long-term HAART to normalize immune dysregulation in severely immunodeficient HIV-infected patients remains unclear. Here we address indices of immune dysregulation in previously severely immunocompromised HIV-infected patients treated with long-term HAART who had achieved increased CD4 T-cell counts and complete suppression of HIV viraemia. METHODS: We examined expression of CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4) and intracellular perforin by CD4 and CD8 lymphocytes from 25 highly selected HIV-infected patients [nadir CD4 T-cell counts <50 cells/microL, >4 years on HAART and >6 months of complete viral suppression (<50 HIV-1 RNA copies/mL)] and 18 HIV-seronegative age- and sex-matched controls. RESULTS: HIV-infected patients had lower percentages of CD28-expressing CD4 lymphocytes and higher percentages of CTLA-4-expressing CD4 lymphocytes than controls. The percentage of CTLA-4-expressing CD4 lymphocytes correlated inversely with that of CD28-expressing CD4 lymphocytes. The proportion of CD4 lymphocytes expressing perforin was generally low. However, more HIV-infected patients than controls had >1% of CD4 lymphocytes expressing perforin [11 of 25 (44%) vs. one of 18 (5.5%)]. The percentage of CD8 lymphocytes expressing perforin did not differ between HIV-infected patients and controls. Amongst HIV-infected patients, the percentage of perforin-expressing CD8 lymphocytes correlated inversely with nadir but not current CD4 T-cell count. CONCLUSIONS: Expression of CD28, CTLA-4 and perforin by CD4 lymphocytes remain dysregulated in HIV-infected patients with previous severe immunodeficiency, despite increased CD4 T-cell counts and control of HIV viraemia by HAART.     

慢性乙型肝炎患者干扰素疗效与CD28阳性外周血单个核细胞的关系

探讨干扰素疗效与慢性乙肝患者CD2 8阳性外周血单个核细胞 (PBMCs)的关系。分离 32例慢性乙肝患者及 8例正常对照PBMCs,以间接免疫荧光流式细胞技术检测CD2 8+ PBMCs,结果显示慢性乙肝患者在干扰素治疗前和结束时CD2 8+ PBMCs均较正常对照组显著降低 (分别为P <0 0 1及P <0 0 5 ) ;干扰素治疗结束时患者CD2 8+ PBMCs水平显著升高 ,与治疗前相比差异具有极显著意义 (P <0 0 1) ;抗病毒治疗 3个月后有 2 1例患者达到完全或部分应答标准 ,11例无应答 ;产生完全或部分应答组 ,在治疗前、后CD2 8+ PBMCs均相应高于无应答组 ;进一步分析表明 ,治疗前完全应答组显著高于无应答组 ,差异具有显著性意义 (P <0 0 5 ) ,而部分应答组虽高于无应答组 ,但差异无显著性意义 (P >0 0 5 )。研究结果提示慢性乙肝患者CD2 8+ PBMCs水平可能与患者对干扰素的应答有关 ,似可作为干扰素疗效预测的指标。     

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。     

CTLA-4 controls follicular helper T-cell differentiation by regulating the strength of CD28 engagement

Cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) is an essential regulator of T-cell responses, and its absence precipitates lethal T-cell hyperactivity. However, whether CTLA-4 acts simply to veto the activation of certain clones or plays a more nuanced role in shaping the quality of T-cell responses is not clear. Here we report that T cells in CTLA-4–deficient mice show spontaneous T-follicular helper (T_FH) differentiation in vivo, and this is accompanied by the appearance of large germinal centers (GCs). Remarkably, short-term blockade with anti–CTLA-4 antibody in wild-type mice is sufficient to elicit T_FH generation and GC development. The latter occurs in a CD28-dependent manner, consistent with the known role of CTLA-4 in regulating the CD28 pathway. CTLA-4 can act by down-regulating CD80 and CD86 on antigen presenting cells (APCs), thereby altering the level of CD28 engagement. To mimic reduced CD28 ligation, we used mice heterozygous for CD28, revealing that the magnitude of CD28 engagement is tightly linked to the propensity for T_FH differentiation. In contrast, other parameters of T-cell activation, including CD62L down-regulation and Ki67 expression, were relatively insensitive to altered CD28 level. Altered T_FH generation as a result of graded reduction in CD28 was associated with decreased numbers of GC B cells and a reduction in overall GC size. These data support a model in which CTLA-4 control of immunity goes beyond vetoing T-cell priming and encompasses the regulation of T_FH differentiation by graded control of CD28 engagement.Control of the magnitude and nature of adaptive immune responses is critical for health. The cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4)/CD28 axis has long been known to control the magnitude of T-cell responses, however whether it also influences their nature has not been clear. Early studies suggested that CD28 may be particularly important for Th2 differentiation (1, 2), although others identified roles for CD28 in both Th1 and Th2 responses (3, 4). It is known that CD28 is an absolute requirement for the differentiation of follicular helper T cells (T_FHs) that support germinal center (GC) formation (5, 6). However, these studies generally make use of CD28-deficient T cells, and therefore, results may reflect a failure of the cells to properly activate, proliferate, or survive, particularly given the known contribution of CD28 to these processes.A key outstanding question is whether CD28 costimulation in vivo is more complex than a binary checkpoint for T-cell priming. It is clear that expression of costimulatory ligands on antigen presenting cells (APCs) fluctuates in response to environmental stimuli, being up-regulated by inflammatory cytokines and TLR agonists and down-regulated by Treg-expressed CTLA-4 (7–11). Thus, variable levels of costimulatory ligands will be available for CD28 binding depending on the microenvironmental context. However, whether this simply alters the number of T cells that achieve the required threshold to commit to a response or whether it influences the nature of the response is not clear. Effective immune homeostasis appears to be reliant on maintaining an appropriate level of CD28 engagement. For example, basal expression of CD28 ligands, in particular dendritic cell-expressed CD86 (12), is critical to Treg homeostasis (13, 14), whereas excessive CD28 engagement in the absence of CTLA-4 results in lethal autoimmunity (15, 16). Nonetheless, distinguishing whether these effects are simply quantitative is not straightforward. Thus, although levels of CD28 ligands are clearly variable in vivo, our understanding of the impact of altering the level of CD28 engagement is still incomplete.To explore the impact of varying levels of CD28 ligation, we have used the CTLA-4–deficient mouse as a model of excessive CD28 stimulation. In these mice, we observed a striking skewing toward T_FH differentiation, with induction of IL-21 and spontaneous formation of GCs. In a complementary approach, we used CD28 heterozygosity to decrease T cell CD28 expression: This revealed that the level of CD28 engagement is tightly coupled to the level of inducible T-cell costimulator (ICOS) induction, T_FH generation, and GC formation, whereas other parameters of T-cell activation were less affected. Finally, we demonstrate that induction of the microRNA cluster miR17-92, recently linked with T_FH differentiation (17, 18), varies proportionally with APC costimulatory ligand expression and is modulated by CTLA-4 deficiency or blockade. Collectively, these data suggest that the CTLA-4/CD28 axis provides quantitative and qualitative control of T-cell help for humoral immunity.     

Increase in CD95 (Fas/APO-1)-positive CD4+ and CD8+ T cells in peripheral blood derived from patients with autoimmune hepatitis or chronic hepatitis C with autoimmune phenomena

BACKGROUND: The expressions of CD95 (Fas/APO-1) and Bcl-2 are determinants of apoptosis in normal lymphocytes, and abnormalities in their expressions might contribute to the induction of autoimmunity. In this study, we examined the expressions of CD95 and Bcl-2 on freshly isolated T and B cells from patients with autoimmune hepatitis (AIH) or chronic hepatitis C associated with autoimmune phenomena (CH-C(AI)). METHODS: The CD95 and Bcl-2 expressions within CD4+ T, CD8+ T, and CD19+ B cell subsets were analysed by two-colour flow cytometry. RESULTS: The surface expression of CD95 was significantly high in both the CD4+ T and CD8+ T cell subsets derived from the patients with AIH and those with CH-C(AI), compared with expression in patients with CH-C and normal subjects. The increase in CD95 expression was associated with the phenotypic conversion of naive CD45RO- to primed CD45RO+ CD4+ T cells. Bcl-2 was detected in the vast majority of peripheral T and B cells. There was no significant difference in the percentage of Bcl-2-positive cells in the CD4+ T cell, CD8+ T cell and CD19+ B cell subsets among the patient groups and normal subjects. CONCLUSIONS: These results indicate that an increase in CD4+ T cells expressing CD45RO and CD95 marks an important subset of AIH and CH-C(AI) patients. These expanded CD95+ CD45RO+ primed T cells most likely reflect a continuous antigen-specific or non-specific activation of T lymphocytes, and/or the persistent presence of activated lymphocytes as a consequence of abnormalities in the peripheral deletion of activated lymphocytes. These persistently activated lymphocytes might play a role in the induction of autoimmunity in AIH and CH-C(AI).