丙型肝炎病毒核心蛋白——免疫逃逸的“核心”？

丙型肝炎病毒（HCV）的特性是可以引起大多数病人的慢性感染。这主要是由于宿主免疫系统无法清除最初的HCV感染。强大的HCV特异性CD4＋和CDg＋T细胞活化与急性感染的清除有关，同时在慢性感染中，针对许多病毒决定基的HCV特异性T细胞的克隆是存在的，但其发生率低且没有发挥有效的功能。慢性HCV感染的异常免疫应答包括固有免疫系统的不完全活化，如单核细胞产生过度的炎性级联反应以及树突状细胞（DC）功能的改变。     

CD4+CD25+调节性T细胞对慢性丙型肝炎患者病毒特异性CD8+T细胞的抑制作用

HCV感染是严重危害人民健康的传染病，易发展成慢性丙型肝炎、肝硬化，且与原发性肝癌密切相关。HCV持续感染的一个重要原因是HCV特异性CD8^＋T细胞数量及功能缺陷，表现在体外增殖能力下降和IFN-γ分泌水平降低。CD4^＋CD25^＋调节性T细胞（T regulatory cells，Treg）主要在机体免疫系统中发挥负向调节作用，在移植物抗宿主病、自身免疫病、过敏性疾病等的发病机制和临床治疗中有潜在应用价值。已有研究表明，     

慢性丙型肝炎病毒感染状态与机体免疫功能关系的探讨

目的：探讨慢性丙型肝炎病毒感染患者HCVRNA增殖状态与T细胞亚群功能及血浆中IL-2和sIL-2R活性的关系。方法：以间接免疫荧光法，ELISA法和RT-PCR分别检测75名慢性HCV感染患者外周血T细胞亚群，IL-2及sIL-2R的水平和HCVRNA。结果：慢性HCV感染患者周围血CD3 ，CD4 淋巴细胞亚群，CD4 ／CD8 比值及IL-2水平均显著低于正常对照组(P<0.01)而sIL-2R明显升高(P<0.01)；血清HCVRNA阳性患者T细胞亚群，CD4 ／CD8 比值及IL-2水平显著低于HCVRNA阴性患者(P<0.01)。结论：慢性HCV感染患者的机体免疫功能紊乱，细胞免疫功能低下，HCVRNA阳性患者较阴性患者更甚，提示细胞免疫功能受抑可能是HCV持续增殖的原因。     

HCV感染患者免疫细胞部分细胞因子分泌情况的初步研究

目的研究与正常人比较丙型肝炎病毒（HCV）感染患者免疫细胞分泌γ干扰素（IFN-γ）、白细胞介素10（IL-10）、肿瘤坏死因子α（TNF-α）及白细胞介素4（IL-4）的细胞频数情况,了解HCV感染对其影响。方法分离外周血单核细胞（PBMCs）,应用IL-10、IFN-γ、TNF-α及IL-4流式抗体进行细胞内因子染色,应用FACSCalibur流式细胞仪及FACSCalibur软件进行检测分析。结果HCV感染患者分泌IL-10、IFN-γ、IL-4的细胞频数在CD4＋CD8-T细胞、CD4-CD8＋T细胞、NK细胞和NKT细胞均发生明显下降;分泌TNF-α的细胞频数在CD4-CD8＋T淋巴细胞及NK细胞出现下降;HCV感染患者NK细胞、NKT细胞分泌IL-10和IFN-γ的细胞频数较CD4＋CD8-T淋巴细胞、CD4-CD8＋T淋巴细胞下降得更加明显。结论HCV感染患者的细胞免疫功能受到明显的损害,细胞因子分泌能力明显减低;固有免疫细胞功能受损可能是HCV感染慢性化的重要原因;细胞因子分泌的调节是抗HCV感染免疫治疗过程中需要调节的方向。     

慢性丙型肝炎外周血淋巴细胞亚群与HCV RNA载量及HCV抗体的相关性分析

目的探讨慢性丙型肝炎(CHC)患者外周血淋巴细胞亚群的变化以及与丙型肝炎病毒(HCV)病毒载量和抗HCV水平的相关性。方法应用流式细胞术检测60例慢性丙型肝炎患者外周血T淋巴细胞亚群及NK细胞的相对数量,与20例正常健康人做比较;应用实时荧光定量RT-PCR对其外周血HCV病毒载量进行检测,分为3组进行分析;化学发光法检测血清抗HCV水平,分2组进行比较分析。另外,分析HCV RNA载量及抗HCV水平与外周血淋巴细胞亚群变化的相关性。结果慢性丙型肝炎患者组外周血CD4+T淋巴细胞比例、NK细胞比例和CD4+/CD8+比值低于正常人组,CD8+T淋巴细胞比例高于正常人组;随着HCV RNA载量的增高CD4+、CD4+/CD8+比值及NK细胞比例逐渐降低,CD8+T淋巴细胞比例逐渐增高。随着抗HCV水平的增高CD4+、CD4+/CD8+比值及NK细胞比例逐渐降低,CD8+T淋巴细胞比例逐渐增高。结论 CHC患者细胞免疫功能存在着较严重的失调,随着HCV病毒复制和机体抗体水平的增高,患者的特异性和非特异性细胞免疫功能均越受到抑制,机体清除病毒的能力越弱,导致病毒不能有效的被清除,使病情反复迁延,造成HCV病毒持续感染,从而促进了HCV感染的慢性化及疾病的进展,少部分患者甚至发生了恶变导致肝细胞癌。     

丙型肝炎病毒感染者外周血淋巴细胞亚群的变化及意义

目的调查丙型肝炎患者外周血淋巴细胞亚群变化及影响因素。方法利用流式细胞术检测241例丙型肝炎患者和117例健康人群外周血淋巴细胞亚群数值,通过回顾性分析,调查我国丙型肝炎人群淋巴细胞亚群变化及其相关的影响因素。结果在健康人群中,CD3＋CD4＋T细胞、CD3＋CD16＋CD56＋NKT细胞频率以及CD4/CD8比值与年龄呈显著正相关;而在慢性丙型肝炎人群中,CD3＋CD4＋T细胞与年龄呈显著正相关,CD3-CD19＋B细胞则与年龄呈显著负相关;在肝硬化人群中,只有CD3-CD16＋CD56＋NK细胞频率与年龄呈显著正相关;在15～49岁的健康人及慢性肝炎人群中,女性CD3＋CD4＋T细胞亚群频率高于男性,而在肝硬化患者中女性CD3-CD19＋B细胞频率低于男性;同时,在HCV感染的不同阶段,CD3-CD16＋CD56＋NK细胞亚群频率均较正常人显著降低,而CD3＋CD8＋T细胞频率则显著升高,在15岁以上人群,CD3-CD19＋B细胞在健康人、慢性肝炎、肝硬化人群中呈持续升高的现象。结论通过回顾性分析健康人群和HCV感染不同阶段人群淋巴细胞亚群的分布特点及其与HCV疾病进展、年龄、性别的关系,为临床科学评价丙型肝炎人群免疫状态提供重要的免疫指标。     

人类免疫缺陷病毒和丙型肝炎病毒重叠感染者的临床及免疫特征

目的 观察人类免疫缺陷病毒(HIV)和HCV重叠感染者与慢性丙型肝炎患者临床特征及HCV特异性细胞毒性T淋巴细胞(CTL)的数量及功能,探讨两组患者免疫功能的差异及其可能的影响因素.方法 以HIV和HCV重叠感染患者59例、慢性丙型肝炎患者36例为研究对象,取治疗前外周血检测肝脏生物化学指标、血常规、外周血T淋巴细胞亚群(CD4+T、CD8+T淋巴细胞计数)及HIV、HCV病毒载量,以酶联免疫斑点法检测HCV特异性CTL的数量和功能,统计学分析两组问免疫功能的差异及与上述检测指标的相关性. 结果 中国河南省有偿献血、单采血浆人群HIV感染者中HIV和HCV重叠感染率达60.8%.ALT、AST值在重叠感染组与HCV组间差异无统计学意义;球蛋白在重叠感染组为(40.3±5.8)g/L,HCV组为(32.8±6.3)g/L,差异有统计学意义(P＜0.01).重叠感染组外周血CD4+T淋巴细胞数明显低于HCV组(P＜0.01),而CD8+T淋巴细胞数高于HCV组(P＜0.01).重叠感染组HCV RNA定量高于HCV组(P＜0.01).重叠感染组对HCV-NS3区肽段的反应强度(每106个外周血单个核淋巴细胞中斑点形成细胞的个数)较HCV组弱,649.34±685.90对比1233.70±1085.16,差异有统计学意义(P＜0.05).重叠感染组白蛋白与HCV病毒载量呈现负相关(r=0.540);重叠感染组对HCV-NS3区肽段反应强度与HIV病毒载量负相关(r=0.356);重叠感染患者CD4+T淋巴细胞数与血小板正相关(P＜0.05).但未见重叠感染组HCV RNA与CD4+T淋巴细胞数量及HIVRNA水平有相关关系.结论 重叠HIV感染有利于HCV的复制,而HIV载量可影响针对HCV的特异性免疫反应,HIV载量高则不利于HCV的清除.慢性丙型肝炎患者重叠HIV感染时,病情易慢性化,预后更差.     

滤泡性辅助性T细胞与HCV感染的相关性

目的检测慢性HCV感染者外周血CD4＋T细胞中滤泡性辅助性T细胞（Tfh）所占比例,ICOS及负性调控因子PD-1、Tim-3在Tfh细胞上的表达。方法以31例HCV感染者、9例HCV感染自愈者（SR-HCV患者）及12例健康志愿者作为研究对象,应用流式细胞术分析外周血中CD4＋CXCR5＋Tfh细胞在CD4＋T细胞中所占比率,同时检测其ICOS、PD-1及Tim-3分子表达,通过酶联免疫吸附法测定血浆中白细胞介素（IL）21及HCV抗体水平,实时定量PCR检测HCV RNA滴度;多组数据比较采用单因素方差分析,双变量之间相关性采用Spearman秩相关分析。结果与健康对照组相比,HCV感染者及自愈者外周血CD4＋T细胞比率升高（P〈0.05）;HCV感染者CD4＋CXCR5＋Tfh细胞比率高于自愈及健康对照（P〈0.05）;HCV感染及自愈者CD4＋CX-CR5＋Tfh细胞ICOS、PD-1、Tim-3显著高于健康对照（P〈0.05）;血清IL-21水平HCV感染者与健康对照无统计学差异（P〉0.05）;HCV感染者HCV RNA载量与Tfh细胞比例呈负相关。结论 CD4＋CXCR5＋Tfh可能参与了抗HCV感染免疫应答。     

急性丙型肝炎中，CD4T细胞效应与中和性抗体及CD8T细胞效应的不同作用

背景和目的：在大多数患者中急性丙型肝炎病毒（HCV）的感染将转为慢性。虽然HCV特异性CD4T细胞的效应与HCV的清除有关，但对于病毒特异性CD8T细胞或者中和性抗体（nAb）的效应及在诱导两者中CD4的辅助作用方面知之甚少。     

外周血T淋巴细胞亚群和慢性丙型肝炎患者HCV复制程度关系的研究

目的分析外周血T淋巴细胞亚群和慢性丙型病毒性肝炎(chronic hepatitis C,CHC)患者的丙型肝炎病毒(hepatitis C virus,HCV)复制程度的关系。方法选取上海市第七人民医院收治的CHC患者65例和健康体检者20名,流式细胞仪检测外周血中的T细胞亚群,荧光定量PCR法检测患者血清HCV RNA复制程度。结果 CD3+T细胞亚群在两组人群中分布相比,差异无统计学意义(P0.05);CD4+T细胞亚群在CHC患者中分布明显低于健康体检者(P0.05),而CD8+T细胞亚群在CHC患者中分布明显高于健康体检者(P0.05)。CD3+T细胞亚群百分率与HCV复制程度无明显相关性(P0.05);CD4+T细胞亚群、CD8+T细胞亚群百分率和CD4+/CD8+比值与HCV复制程度有明显相关性(P0.05)。结论 CHC患者外周血T淋巴细胞亚群比例改变与导致HCV感染慢性化密切相关。HCV RNA复制程度增加进一步导致T细胞亚群紊乱,CD4+/CD8+比值的动态变化可提示HCV感染者细胞免疫功能的变化。     

Increased frequency of interferon-gamma-producing peripheral blood CD4+ T cells in chronic hepatitis C virus infection

OBJECTIVES: To determine the profile of cytokine secretion by CD4+ T helper (Th) cells in chronic hepatitis C virus (HCV) infection, we used flow cytometry to determine the percentage of interferon (IFN)-gamma and interleukin (IL)-4 producing cells from CD4+ T lymphocytes in peripheral blood obtained from patients chronically infected with HCV. METHODS: Peripheral blood mononuclear cells isolated from 89 HCV infected subjects (22 asymptomatic carriers, 56 patients with chronic hepatitis, and 11 patients with liver cirrhosis) and 24 healthy controls were stained with surface CD4 and intracellular IFN-gamma and IL-4. Serum soluble IL-2 receptor (sIL-2R) levels were analyzed by ELISA. RESULTS: The frequency of IFN-gamma producing CD4+ cells in asymptomatic HCV carriers, patients with chronic hepatitis, and patients with liver cirrhosis were significantly higher than those of healthy controls (p<0.01, respectively). In contrast, the percentages of IL-4-producing CD4+ cells were very low, and there were no significant correlations with disease progression. A significant elevation in serum sIL-2R levels was found in chronic HCV infection compared to healthy controls, and serum sIL-2R levels significantly correlated with the frequency of IFN-gamma-producing cells. CONCLUSIONS: In HCV infected subjects, both serum sIL-2R and IFN-gamma are increased in chronic HCV infection no matter the stage of disease, meaning they are no different in asymptomatic carriers, patients with chronic hepatitis, and patients with liver cirrhosis, and that Th1 cytokine or Th1 cells may participate in the pathogenesis of liver damage in chronic HCV infection.     

Quantitative and functional differences in CD8+ lymphocyte responses in resolved acute and chronic hepatitis C virus infection

CD8⁺ T lymphocyte responses are important in the clearance of viral infections. In chronic infections they may contribute to pathogenesis. To investigate the role of CD8⁺ T lymphocyte responses in viral clearance and chronic hepatitis C we have compared hepatitis C virus (HCV) specific cytotoxicity and interferon-gamma (IFN-γ) production in patients with resolved-acute, and chronic HCV infection. CD8⁺ T cell responses to a panel of 13 HCV T cell peptide epitopes were studied using Elispot assays of IFN-γ production and chromium release cytotoxicity assays. Responses of seven patients with resolved acute HCV infection were compared with those of 14 chronically infected patients. HCV-specific cytotoxicity differentiated the two populations of patients. The majority (71%) of patients with resolved acute infection tested positive to 42% of relevant peptides compared with the minority (28%) of patients with chronic hepatitis C ( P =0.03) who responded to only 8% of relevant peptides ( P =0.0009). In contrast, HCV-specific IFN-γ production was detected in 86% of patients with either resolved or chronic infection in response to 42% and 35%, respectively, of relevant peptides tested (not significant). In patients with chronic infection the magnitude of the HCV-specific IFN-γ production was inversely correlated to viral load ( R ²=0.52; P =0.042). Failure to clear HCV infection may be attributable to the presence of noncytolytic IFN-γ producing CD8⁺ T lymphocytes in chronically infected patients. However these CD8⁺ T cells may play a beneficial role in contributing to the control of viral load in chronic hepatitis C.     

Hepatitis C‐specific effector and regulatory CD4 T‐cell responses are associated with the outcomes of primary infection

Clearance of primary hepatitis C virus (HCV) infection has been associated with strong and broadly targeted cellular immune responses. This study aimed to characterize HCV‐specific CD4+ effector and regulatory T‐cell numbers and cytokine production during primary infection. Antigen‐specific CD4+ T‐cell responses were investigated in a longitudinal cohort of subjects from pre‐infection to postoutcome, including subjects who cleared [n=12] or became chronically infected [n=17]. A cross‐sectional cohort with previously cleared, or chronic infection [n=15 for each], was also studied. Peripheral blood mononuclear cells were incubated with HCV antigens and surface stained for T‐effector (CD4+CD25^highCD134+CD39‐) and T‐regulatory (CD4+CD25^highCD134+CD39+) markers, and culture supernatants assayed for cytokine production. Contrary to expectations, the breadth and magnitude of the HCV‐specific CD4+ T‐cell responses were higher in subjects who became chronically infected. Subjects who cleared the virus had HCV‐specific CD4+ T‐cell responses dominated by effector T cells and produced higher levels of IFN‐γ, in contrast to HCV‐specific CD4+ T‐cell responses dominated by regulatory T cells and more IL‐10 production in those who became chronically infected. Better understanding of the role of antigen‐specific CD4+ T‐cell responses in primary HCV will further define pathogenesis and help guide development of a preventative vaccine.     

Hepatitis C viraemia reversibly maintains subset of antigen‐specific T‐bet+ tissue‐like memory B cells

Background: Chronic antigen exposure and/or ageing increases the frequency of T‐box expressed in T cells (T‐bet)‐expressing B‐lymphocytes in mice. The frequency and significance of B‐cell T‐bet expression during chronic hepatitis C (HCV) infection in human subjects has never been described. Methods: Healthy controls, cirrhotic and noncirrhotic HCV‐infected patients, and non‐HCV patients with cirrhosis were recruited. Peripheral blood mononuclear cells were phenotyped for expression of T‐bet and related markers by flow cytometry. In a subset of patients who underwent antiviral therapy and were cured of HCV infection (sustained virological response), the dynamics of T‐bet expression in B cells was monitored. After cure, convalescent B cells were tested for T‐bet expression after re‐exposure to infected plasma or recombinant HCV proteins. Results: Forty‐nine patients including 11 healthy donors, 30 hepatitis C‐infected individuals (nine with liver cancer, 13 with cirrhosis, eight without cirrhosis) and eight patients with cirrhosis due to non‐HCV‐related cause were recruited. We found that B cells in patients with chronic HCV exhibited increased frequency of T‐bet+ B cells relative to noninfected individuals (median 11.5% v. 2.2%, P<.0001) but that there were no significant differences between noncirrhotic, cirrhotic and cancer‐bearing infected individuals. T‐Bet⁺ B cells expressed higher levels of CD95, CXCR3, CD11c, CD267 and FcRL5 compared to T‐bet^? B cells and predominantly exhibit a tissue‐like memory CD27^?CD21^? phenotype independent of HCV infection. T‐bet⁺ B cells in HCV‐infected patients were more frequently class‐switched IgD^?IgG⁺ (40.4% vs. 26.4%, P=.012). Resolution of HCV infection with direct‐acting antiviral (DAA) therapy leads to a marked reduction in the frequency of T‐bet⁺ B cells (median 14.1% pretreatment v. 6.7% end of treatment v. 6.1% SVR12, P≤.01). Re‐exposure of convalescent (cured) B cells to viremic plasma and recombinant HCV E2 protein led to re‐expression of T‐bet. Conclusion: Chronic antigenemia in chronic HCV infection induces and maintains an antigen‐specific T‐bet⁺ B cell. These B cells share markers with tissue‐like memory B cells. Antigen‐driven T‐bet expression may be a critical suppressor of B‐cell activation in chronic HCV infection.     

Different aspects of CD4 T cells that lead to viral clearance or persistence of HCV infection

More than 170 million people worldwide are infected with hepatitis C virus (HCV). A characteristic of this virus is a high tendency toward chronic infection. Several factors affect the viral outcome after infection. Among them, HCV-specific CD4 T cells are thought to play a crucial role in controlling viremia. Cumulative data showed that spontaneously resolved individuals have vigorous CD4 T-cell responses to a broad spectrum of HCV antigens and maintain these responses over a long period of time, whereas chronically infected patients lose their CD4 T-cell responses in the acute phase of infection. Although several possibilities of why CD4 T cells lose their function have been proposed, the mechanisms are not completely understood. Moreover, there is another subset of CD4 T cells called regulatory T cells (Tregs). These cells suppress immune reaction of T cells, B cells, and antigen-presenting cells, and are thought to protect organs from immune overreaction and autoimmunity. An increasing amount of data supports the possibility that Tregs participate in the mechanism of HCV persistence. It is obvious that CD4 T cells are the main effectors controlling HCV outcome. To achieve a better prognosis, we need to understand the mechanism of how HCV earns its chronicity by escaping from host cellular immune attacks. In this review, we will focus on the role of HCV-specific T cells in controlling viremia, particularly the aspects of these cells being either inhibitors or propellers of chronic infection.     

Specific cellular immune response and cytokine patterns in patients coinfected with hepatitis C virus and Schistosoma mansoni

Patients coinfected with hepatitis C virus (HCV) and Schistosoma mansoni show high incidence of viral persistence and accelerated fibrosis. To determine whether immunological mechanisms are responsible for this alteration in the natural history of HCV, the HCV-specific peripheral CD4(+) T cell responses and cytokines were analyzed in patients with chronic hepatitis C monoinfection, S. mansoni monoinfection, or HCV and S. mansoni coinfection. An HCV-specific CD4(+) proliferative response to at least 1 HCV antigen was detected in 73.3% of patients infected with HCV, compared with 8.6% of patients coinfected with HCV and S. mansoni. Stimulation with HCV antigens produced a type 1 cytokine profile in patients infected with HCV alone, compared with a type 2 predominance in patients coinfected with HCV and S. mansoni. In contrast, there was no difference in response to schistosomal antigens in patients infected with S. mansoni alone, compared with those coinfected with HCV and S. mansoni. These findings suggest that the inability to generate an HCV-specific CD4(+)/Th1 T cell response plays a role in the persistence and severity of HCV infection in patients with S. mansoni coinfection.     

Hepatic compartmentalization of exhausted and regulatory cells in HIV/HCV‐coinfected patients

Accelerated intrahepatic hepatitis C virus (HCV) pathogenesis is likely the result of dysregulation within both the innate and adaptive immune compartments, but the exact contribution of peripheral blood and liver lymphocyte subsets remains unclear. Prolonged activation and expansion of immunoregulatory cells have been thought to play a role. We determined immune cell subset frequency in contemporaneous liver and peripheral blood samples from chronic HCV‐infected and HIV/HCV‐coinfected individuals. Peripheral blood mononuclear cells (PBMC) and biopsy‐derived liver‐infiltrating lymphocytes from 26 HIV/HCV‐coinfected, 10 chronic HCV‐infected and 10 HIV‐infected individuals were assessed for various subsets of T and B lymphocytes, dendritic cell, natural killer (NK) cell and NK T‐cell frequency by flow cytometry. CD8⁺ T cells expressing the exhaustion marker PD‐1 were increased in HCV‐infected individuals compared with uninfected individuals (P = 0.02), and HIV coinfection enhanced this effect (P = 0.005). In the liver, regulatory CD4⁺CD25⁺Foxp3⁺ T cells, as well as CD4⁺CD25⁺PD1⁺ T cells, were more frequent in HIV/HCV‐coinfected than in HCV‐monoinfected samples (P < 0.001). HCV was associated with increased regulatory T cells, PD‐1⁺ T cells and decreased memory B cells, regardless of HIV infection (P ≤ 0.005 for all). Low CD8⁺ expression was observed only in PD‐1⁺CD8⁺ T cells from HCV‐infected individuals and healthy controls (P = 0.002) and was associated with enhanced expansion of exhausted CD8⁺ T cells when exposed in vitro to PHA or CMV peptides. In conclusion, in HIV/HCV coinfection, ongoing HCV replication is associated with increased regulatory and exhausted T cells in the periphery and liver that may impact control of HCV. Simultaneous characterization of liver and peripheral blood highlights the disproportionate intrahepatic compartmentalization of immunoregulatory T cells, which may contribute to establishment of chronicity and hepatic fibrogenesis in HIV coinfection.     

Preferential loss of IL-2-secreting CD4+ T helper cells in chronic HCV infection

Hepatitis C virus (HCV) becomes persistent in the majority of infected individuals. In doing so, the virus evades host adaptive immune responses, although the mechanisms responsible in this evasion are not clear. Several groups have demonstrated weak or absent HCV-specific CD4+ T cell responses during chronic HCV infection using proliferation assays and, more recently, class II tetramers. However, the functional status of HCV-specific CD4+ T cells in resolved and persistent infection is poorly understood. Using interferon gamma (IFN-gamma) and interleukin 2 (IL-2) enzyme-linked immunospot assays, we analyzed cytokine secretion patterns in chronically infected patients and compared them with those with resolved infection. In the spontaneous resolver group, strong IL-2 secretion in relation to IFN-gamma secretion was observed. However, in the persistently infected group, a consistent and significant loss of IL-2-secreting cells, compared with IFN-gamma-secreting cells, was identified. In vitro addition of IL-2 had a substantial effect in restoring CD4+ T cell activity. In conclusion, failure of IL-2 secretion, as opposed to physical deletion or complete functional unresponsiveness, appears to be an important determinant of the status of CD4+ T cell populations in chronic HCV infection. Loss of IL-2 secretory capacity may lead to disruption of IFN-gamma and proliferative function in vivo-a status that characterizes the cellular immune response in both CD4+ and CD8+ compartments in chronic disease.     

CD8+ cell responses to hepatitis C virus (HCV) in the liver of persons with HCV-HIV coinfection versus HCV monoinfection

OBJECTIVE: Cellular immune responses are difficult to detect in the peripheral blood of persons with chronic hepatitis C virus (HCV) infection. We sought to determine whether T cell responses were present in the liver of patients with human immunodeficiency virus (HIV) and HCV coinfection. METHODS: T cells were expanded from liver-biopsy samples from 10 patients coinfected with HIV and HCV (median CD4(+) cell count, 456 cells/mm(3)) and 8 patients infected with HCV alone. CD8(+) cell responses were detected by use of a modified enzyme-linked immunospot (ELISpot) assay with recombinant vaccinia virus, and CD4(+) cell responses were detected by use of ELISpot with recombinant HCV proteins core, nonstructural (NS) 3, and NS5. RESULTS: Intrahepatic CD8(+) cell responses to HCV were detected in 7 of 10 patients coinfected with HCV and HIV (median frequency, 638 spot-forming cells [sfc]/1 x 10(6) cells) and were similar to those observed in patients singly infected with HCV (7/8; median, 647 sfc/1 x 10(6) cells). Intrahepatic HCV-specific CD4(+) cell responses were also comparable in both groups and correlated with the intrahepatic CD8(+) cell responses (r=0.59; P=.03). CONCLUSION: HCV-specific CD8(+) cell responses are present in the liver of persons with chronic HCV infection even when they are coinfected with HIV; these correlate with intrahepatic HCV-specific CD4(+) cell responses.     

Antiviral CD8-mediated responses in chronic HCV carriers with HBV superinfection

Hepatitis B virus (HBV) superinfection in chronic hepatitis C represents a natural model to investigate whether or not hepatitis C virus (HCV) can influence priming and maturation of antiviral T cells; whether or not HBV superinfection, which is known to determine control of HCV replication, can restore HCV-specific T cell responsiveness; and whether or not cytokines stimulated by HBV infection can contribute to HCV control. To address these issues, the function of CD8 cells specific for HBV and HCV was studied longitudinally in two chronic HCV patients superinfected with HBV. Patients with acute hepatitis B were also examined. Frequency and function of HBV tetramer+ CD8 cells were comparable in patients acutely infected with HBV with or without chronic HCV infection. HBV-specific CD8 cell function was efficiently expressed irrespective of serum HCV-RNA levels. Moreover, fluctuations of HCV viremia at the time of HBV superinfection were not associated with evident changes of CD8 responsiveness to HCV. Finally, no correlation was found between serum levels of interferon alpha, interleukin (IL)-12, IL-10, or IL-18 and control of HCV replication. In conclusion, HCV did not affect the induction of primary and memory HBV-specific CD8 responses. HCV-specific CD8 responses were undetectable when HCV-RNA was negative, showing that inhibition of HCV replication in the setting of a HBV superinfection was not sufficient to induce a restoration of CD8 reactivity against HCV.