Flow cytometry CD4+/CD8+ ratio of liver-derived lymphocytes correlates with viral replication in chronic hepatitis B.

T lymphocytes have been assumed to play an essential role in tissue injury in patients with chronic hepatitis B. As hepatitis B virus (HBV) is considered as a major factor controlling liver inflammation, we assessed whether a particular T lymphocyte subset could be preferentially detected in the liver in accordance with viral replication. Liver-derived lymphocytes and peripheral blood lymphocytes were analysed by flow cytometry in 21 patients with histologically confirmed chronic hepatitis B without cirrhosis. Viral replication was quantified by hybridization of serum HBV DNA. Eleven patients exhibited an active viral replication with serum HBV DNA ranging from 10 to 388 pg/ml at the time of the liver biopsy, whereas 10 patients had no detectable serum HBV DNA. In patients exhibiting viral replication, CD4+/CD8+ ratios of liver-derived lymphocytes were significantly higher (P < 0.05) than those obtained in patients without viral replication. In contrast, the percentage of T cells expressing the gamma/delta receptor and that of CD2+/CD57+ cells were similar in both groups of patients. Furthermore, in patients exhibiting viral replication, CD4+CD8+ ratios of liver-derived lymphocytes correlated with serum HBV DNA levels (P < 0.001). No relationship between CD4+/CD8+ ratio of liver-derived and peripheral blood lymphocytes was observed. Our data indicate that, in patients with chronic hepatitis B, the CD4+/CD8+ ratio of liver-derived lymphocytes correlates with viral replication. This suggests that in situ helper/inducer CD4+ T lymphocytes may positively regulate the cytotoxic T cell activity in patients with HBV-related chronic hepatitis.     

Analysis of the CD8-positive T cell response in Japanese patients with chronic hepatitis C using HLA-A*2402 peptide tetramers

Hepatitis C virus (HCV)-specific CD8+ cytotoxic T lymphocytes (CTL) contribute to viral clearance in acute, self-limited hepatitis C as well as to liver cell injury in the more frequent cases with chronic hepatitis C. Although HLA class I-peptide tetramers have been used to detect circulating HCV epitope-specific CTL with a high sensitivity and specificity, this technique has been targeted exclusively to the most frequent HLA haplotypes in the Caucasian population and the large number of HCV-infected Asian patients, most of whom are HLA-A24 positive, have not been studied. The current study determines the frequency, phenotype, and clinical significance of HCV-specific CD8(+) T lymphocytes with five different HLA-A*2402 tetramers in 43 HCV infected Japanese patients and 32 controls. Overall, tetramer(+) cells were detected in the blood of 33 of 43 patients at frequencies of 0.064-0.75% CD8(+)CD4(-)CD14(-)CD19(-) T lymphocytes. Interestingly, although the T cell response was always targeted multispecifically against epitopes in different HCV proteins, the relative frequency of cells stained with individual tetramers differed between patients. Furthermore, tetramer(+)CD8(+) T lymphocytes were highly activated, but the phenotypes of different tetramer(+) cells varied in each patient. In conclusion, HLA-A24 restricted, HCV-specific CD8(+) T lymphocytes are found at similar frequencies in Asian patients as HLA-A2 restricted, HCV-specific CD8(+) T lymphocytes in Caucasian patients. Differences in the frequency and activation status of individual tetramer(+) cell populations suggest that CD8(+) T lymphocytes with different HCV epitope specificity may mediate differential pathogenetic effects in chronic hepatitis C.     

HCV感染外周血单个核细胞及其对T淋巴细胞亚群的影响

目的：研究丙型肝炎病毒（ＨＣＶ）感染外周血单个核细胞（ＰＢＭＣ）的情况及其对Ｔ淋巴细胞亚群的影响。方法：运用非同位素原位杂交（ＮＩＳＨ）法和链酶亲和素－生物素（ＳＡＢＣ）法分别检测２０例慢性丙型肝炎患者ＰＢＭＣ中的ＨＣＶ－ＲＮＡ和非结构（Ｎｏｎｓｔｒｕｃｔｕｒａｌ,ＮＳ）蛋白ＮＳ５抗原,同时用ＳＡＢＣ法检测其Ｔ淋巴细胞亚群。结果：８例（４０．０％）患者的ＰＢＭＣ中ＨＣＶ－ＲＮＡ呈构（Ｎｏｎｓｔｒｕ     

Differential expression of perforin and granzyme B in the liver of patients with chronic hepatitis C

T lymphocytes have been reported to be the predominant inflammatory cells in the liver of patients with chronic hepatitis C. On activation, CD8+ T lymphocytes can exert their cytolytic activity by releasing their granule components, notably perforin and granzyme B. The aim of the present study was to assess whether the granule cytolytic pathway was used by liver-infiltrating CD8+ T lymphocytes. Immunostaining for perforin and granzyme B was performed in 25 patients with chronic hepatitis C, according to the disease activity and their virologic status. Cells stained for perforin and for granzyme B represented 0.15% and 0.10% of the total liver-infiltrating CD8+ T lymphocytes, respectively. Perforin was expressed mainly by activated CD8+ T lymphocytes located in liver lobules. In contrast, granzyme B was expressed mainly by activated CD8+ T lymphocytes located in interface hepatitis and portal tracts. The results were similar in the different groups of patients, whatever the disease activity. In conclusion, this is the first study showing a differential expression of granule components of CD8+ T lymphocytes in the same tissue in vivo. Perforin and granzyme B may be differently expressed by liver-infiltrating CD8+ T lymphocytes, according to their localization in the different specific compartments of the liver, in patients with chronic hepatitis C.     

STUDY ON PERIPHERAL BLOOD MONONUCLEAR CELL(PBMC) PROLIFERATIVE RESPONSES TO DIFFERENT HCV ANTIGENS IN PATIENTS WITH HEPATITIS C

为探讨丙型肝炎(HC)病人细胞免疫功能和丙型肝炎病毒(HCV)的致病机制及机体对其免疫保护作用,收集24例HC病人(急性3例,慢性21例),用3H-TdR掺入法研究病人外周血单个核细胞(PBMC)对不同HCV抗原增殖反应,并用流式细胞仪(FACS)检测了PBMC中CD4+、CD8+淋巴细胞亚群在HCV抗原刺激后的变化.结果:HC病人PBMC对HCV合成肽CP9,NS和基因重组抗原C,E1,E2,NS3刺激后出现不同程度增殖反应,刺激指数(SI)分别为1.69±0.51,1.61±0.54,1.68±0.58,1.49士0.44,1.44±0.44和1.33±0.33.3例急性HC中2例病人的PBMC对HCV抗原呈有效增殖反应(SI≥2.1),且血清HCVRNA阴转伴ALT正常.细胞表型分析显示:增殖的细胞表型是CD4+淋巴细胞,而CD8+淋巴细胞增殖反应较弱.结论:HC病人PBMC确实存在对HCV抗原的增殖反应;CD4+淋巴细胞比CD8+淋巴细胞增殖反应要强,急性HC病人PBMC对HCV抗原有效的增殖反应预示可能有良好的临床愈合.     

Prominent proliferative response of peripheral blood mononuclear cells to a recombinant non-structural (NS3) protein of hepatitis C virus in patients with chronic hepatitis C.

The proliferative response of peripheral blood mononuclear cells (PBMC) to a recombinant non-structural (NS3) protein of hepatitis C virus (HCV) was studied in 41 patients with chronic hepatitis C. Of them, 28 had chronic persistent hepatitis (CPH) and 13 chronic active hepatitis (CAH). The positive proliferation rate of PBMC to the recombinant NS3 protein, T9Ag, was 66% in the 41 patients (77% in CAH versus 61% in CPH; P > 0.05) when stimulation index (SI) = 4 was set as the cut-off value. However, mean SI of CAH patients was significantly higher than that of CPH patients (8.3 +/- 5.2 versus 5.1 +/- 3.6; P < 0.05). Six other chronic hepatitis patients who were repeatedly negative for anti-HCV antibody but positive for serum HCV RNA also had an SI of > or = 4.0. The frequency of cellular immune response to the T9Ag is among the highest results obtained by using HCV antigens tested so far. Our studies thus indicate that NS3 is an immunologically important region of HCV for T cells. Moreover, the proliferative response to T9Ag may help to establish hepatitis C etiology in chronic hepatitis patients who are seronegative with currently available anti-HCV assays.     

Intrahepatic CD4 T-Cell apoptosis is related to METAVIR score in patients with chronic hepatitis C virus

Hepatitis C virus (HCV) infection leads to liver injury, which is thought to be immune-mediated. Apoptosis of hepatic T cells could influence histological damage. We quantified peripheral and intrahepatic T-cell apoptosis in 28 patients with chronic hepatitis C by using cytofluorometric techniques. METAVIR score and HCV plasma viral load were determined. Six liver biopsies, obtained from controls without chronic hepatitis during hepatobiliary surgery, served as controls. In patients, liver T-cell apoptosis was upregulated compared to peripheral T cells: 35 versus 7% for CD4+ and 56 versus 13% for CD8+ T cells (P < 0.001). Liver T-cell apoptosis levels from patients were increased compared to controls for both CD4+ (P = 0.041) and CD8+ T cells (P = 0.007). Nine patients exhibiting METAVIR scores A and F < or = 1 showed higher intrahepatic CD4+ T-cell apoptosis compared to the 19 patients with a higher METAVIR score (P = 0.001) and both histological activity and fibrosis were related to apoptosis level. There was also an inverse relationship between the level of intrahepatic CD8+ T-cell apoptosis and serum transaminase activity (P = 0.023). Our study shows immune compartmentalization, suggesting that the study of peripheral blood lymphocytes may not be fully relevant to the pathophysiology of HCV hepatitis, and that the severity of liver injury is inversely correlated with intrahepatic CD4+ T-cell apoptosis.     

T cell receptor excision circles (TRECs), CD4+, CD8+, and their CD45RO+, and CD45RA+, subpopulations in hepatitis C virus (HCV)-HIV-co-infected patients during treatment with interferon alpha plus ribavirin: analysis in a population on effective antiretroviral therapy

Interferon (IFN)-alpha induced CD4(+) T lymphopenia is a toxic effect of the treatment of chronic hepatitis C virus (HCV) in human immunodeficiency virus (HIV)-co-infected patients. To increase the knowledge about this secondary effect, we performed an analysis of the evolution of the T cell receptor excision circles (TRECs), CD4(+) and CD8(+) T cells and of their CD45RO(+) and CD45RA(+) subpopulations during the treatment of chronic hepatitis HCV with peginterferon alpha (pegIFN-alpha) + ribavirin. Twenty HCV/HIV-co-infected patients, with undetectable HIV load after highly active antiretroviral therapy (HAART), were treated with pegIFN-alpha + ribavirin. TRECs were determined using real-time polymerase chain reaction. CD4(+) and CD8(+) T cells and their CD45RO(+) and CD45RA(+) subpopulations were analysed by two-colour flow cytometry. Median baseline CD4(+) and CD8(+) T cells were 592 mm(3) and 874 mm(3), respectively. Median baseline CD45RO(+) subpopulation was 48% for CD4(+) T and 57% for CD8(+) T lymphocytes. A progressive decrease in both T cell populations, as well as of their CD45RO(+) and CD45RA(+) subpopulations, was detected, with a difference between the baseline and nadir levels approaching 50%. The evolution of T cell populations and TRECs was independent of the response to the treatment. T lymphocytes and their subpopulations returned to baseline levels at 24 weeks after the end of treatment, with the exception of the T CD4(+) CD45RA(+) subpopulation. The ratio of CD4(+) CD45RO(+)/CD4(+) CD45RA(+) increased from 0.89 (baseline) to 1.44 (24 weeks after the end of the therapy). TRECs/ml did not return to the basal values. In conclusion, a significant reduction of CD4(+) and CD8(+) T cells, and of their CD45RA(+) and CD45RO(+) subpopulations, in HIV/HCV co-infected patients treated with pegIFN-alpha was observed. Both subpopulations increased after the suppression of treatment, but the CD4(+) CD45RA subpopulation did not reach the basal levels as a consequence, at least in part, of a decrease in thymic production.     

Post-transplant reactivation of hepatitis C virus: lymphocyte infiltration and the expression of adhesion molecules and their ligands in liver allografts

Hepatitis C virus (HCV) recurrence after liver transplantation has been associated with chronic rejection. Biopsies from 10 patients with post-transplant HCV were examined for expression of adhesion molecules ICAM-1, VCAM-1, and ELAM-1, number of lymphocytes positive for their ligands LFA-1, VLA-4, and SLeX, and activation markers MHC class II antigens and IL2-R by immunohistochemistry. The phenotypes of the graft-infiltrating lymphocytes were determined. Results were compared to those for patients with normal graft function or rejection. Five recipients with HCV reactivation and one with de novo HCV had a biopsy available showing induction of ICAM-1 in sinusoidal endothelium (p<0.05) and hepatocytes (p<0.01), and Class II antigens in hepatocytes (p<0.01), compared to normal controls. Lymphocytes in the graft infiltrate expressed LFA-1, VLA-4, and Class II antigens, but IL2-R was not significantly expressed. CD3+, CD4+, and CD8+ cells were observed. In our study, HCV recurrence was not associated with acute or chronic rejection, and the inflammation was due to the viral infection.     

Lymphocyte and macrophage phenotypes in chronic hepatitis C infection. Correlation with disease activity.

The pathogenesis of chronic hepatitis C and the mechanisms underlying progressive liver disease in patients with chronic hepatitis C infection are poorly understood. To demonstrate which inflammatory cells might be responsible for the necroinflammatory damage in chronic hepatitis C infection, we have correlated the phenotype of the intrahepatic lymphocytes and macrophages with histological activity in liver biopsy and explant specimens from 19 patients with chronic hepatitis C infection. In all stages of disease, more CD8+ than CD4+ lymphocytes were found. However, histologically active versus histologically mild hepatitis was associated with a trend toward greater parenchymal concentrations of CD4+ lymphocytes (0.71 +/- 0.27 per 10(4) microns 2 versus 0.35 +/- 0.15; not significant), significantly less parenchymal CD8+ lymphocytes (0.90 +/- 0.1 versus 1.70 +/- 0.3; t = 2.32, P = 0.03) and a greater parenchymal CD4/CD8 ratio (4.1 +/- 2.8 versus 0.91 +/- 0.3; t = 1.65, P = 0.07). No difference was found in the number of cells containing cytotoxic granules between the two groups. Greater numbers of CD4+ lymphocytes were found in liver biopsy specimens with little or no staining for hepatitis C virus antigen (1.47 +/- 0.88 versus 0.27 +/- 0.27; t = 2.28, P < 0.05). No significant differences were found in the macrophage subsets between the three stages of disease. Our data suggest that active histological disease in chronic hepatitis C infection may be associated with an increase in CD4+ lymphocytes and suggest that CD4+ T cells may play an important role in the hepatic injury in these patients.     

Inflammatory markers in chronic hepatitis C

 To test the hypothesis that inflammation in hepatitis C follows mechanisms common to immune-activated pathways, the distributions of T and B cells, adhesion molecules and transforming growth factor-β (TGF-β) were assessed in liver biopsies with chronic inflammation due to hepatitis C (HCV, n=8) and other causes (non-HCV, n=10). Frozen sections were immunostained using primary antibodies to CD2, CD20, CD4, CD8, intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM)-1, HLA-DR, lymphocyte function-associated antigen (LFA)-1, and TGF-β. Inflammatory cells positive for each immunophenotypic marker were counted, and positive staining for adhesion molecules, HLA-DR and TGF β was graded in triads and lobules and compared in HCV and non-HCV biopsies. In all biopsies, T cells were more frequent than B cells, both in triads and lobules. CD20+, CD4+, CD8+ and LFA-1+ cells were increased in HCV compared to non-HCV biopsies. Portal lymphoid aggregates were present in 6 of 8 HCV biopsies and 3 of 10 non-HCV biopsies. Aggregates consisted of CD20+, CD4+, CD8+ and LFA-1+ cells, and ICAM-1 and VCAM-1 were increased. Sinusoidal lining cells in HCV biopsies and non-HCV biopsies with inflammation expressed HLA-DR, ICAM-1, and CD4. TGF-β was increased in foci of necrosis. Inflammation in chronic HCV involves common immune-mediated cellular effector pathways and the inflammation in the portal triads represents aggregation of both T and B cells, mediated in part by upregulation of adhesion molecules on portal stromal cells; this is possibly in response to antigens draining from necroinflammatory foci in the lobules. TGF-β is increased in active necroinflammatory foci, but not in portal lymphoid aggregates. Received: 5 November 1996 / Accepted: 18 February 1997     

丙型肝炎病毒非结构区5个细胞毒性T细胞表位的鉴定

目的 采用T细胞表位预测软件结合体外实验鉴定丙型肝炎病毒(HCV)特异性细胞毒性T细胞(CTL)表位.方法 采用T表位预测软件Rankpep预测HCV特异性CTL表位,选择候选CTL表位加以合成;用候选CTL表位肽分别刺激HCV感染者以及健康志愿者的外周血单个核细胞(PBMC),采用酶联免疫斑点试验(ELISPOT)检测PBMC中肽特异性分泌IFN-γ的斑点形成细胞(spots forming cells,SFC)的水平,采用细胞内细胞因子染色(intracellular cytokine staining,ICS)检测PBMC中肽特异性IFN-γ+CD8+T细胞的水平.结果 用5条候选CTL表位肽[NS3 450(TVPQDAVSR)、NS3 594(GPTPLLYRL)、NS4b 78(SMMAFSAAL)、NS5a 416(SEENVSVVF)和NS5a 367(TVSSALAEL)]分别刺激10个HCV感染者和2个健康者的PBMC后,健康者的PBMC不产生IFN-γ而7个HCV感染者的PBMC产生IFN-γ;HCV感染者的PBMC中肽特异性分泌IFN-γ的细胞的频率为(5-36)SFC/105 PBMC,肽特异性IFN-γ+CD8+T细胞占总CD8+T细胞的百分比为0.02%～0.25%.结论 ELISPOT结果和ICS结果证实5条肽NS3 450、NS3 594、NS4b 78、NSSa 416和NS5a 367为全新的HCV特异性CTL表位.     

Concurrent hepatitis C virus and hepatitis delta virus superinfection in patients with chronic hepatitis B virus infection.

Since hepatitis C virus (HCV) and hepatitis delta virus (HDV) are transmitted by the same routes as hepatitis B virus (HBV), simultaneous or concurrent HCV and HDV infection in patients with chronic HBV infection may occur. To test this hypothesis and to examine the clinicohistological and immunopathological presentations of such multiple hepatitis virus infections, acute and/or convalescent serum specimens from 86 patients with acute HDV superinfection were tested by enzyme immunoassay for antibodies to HCV. Of the 86 patients, 18 (20.9%) were associated with HCV infection. Although patients with early mortality cannot be evaluated by the HCV markers used in this study, the results showed that the clinical and histologic features were similar except that patients with HCV infection were older than those without HCV infection (P less than 0.01). Immunopathological studies carried out within 2 months after the onset of acute HDV superinfection demonstrated that hepatitis B core antigen (HBcAg) was not detected in any patient and HDV antigen was detected in 18.2% of the patients with HCV infection whereas HBcAg and HDAg were found in 7% and 65.1%, respectively, of those without HCV coinfection (P less than 0.02). It is concluded that concurrent HCV and HDV superinfections can and do occur in patients with chronic HBV infection. In these triple viral infections, HCV may even transiently suppress HDV and HBV.     

IgM antibody to a hepatitis C virus core peptide (CP14) for monitoring activity of liver disease in patients with acute or chronic hepatitis C

Antibodies to the hepatitis C virus (HCV) core of various immunoglobulin classes were determined by enzyme immunoassays with three synthetic peptides, CP14 (amino acids 5-40 of the core protein), CP10 (5-23), and CP9 (39-74). In 135 patients with chronic type C liver disease, anti-CPU, anti-CP10, and anti-CP9 of IgG class were detected in 99%, 94%, 82%, respectively; those of IgM class in 86%, 69%, and 39%; and those of IgA class in 56%, 40%, and 4%. Thus anti-CP14 was more prevalent than anti-CPlO or anti-CP9 in every immunoglobulin class. The prevalence of IgM anti-CP14 was much higher (P < 0.001) in patients (116/135 or 86%) than in asymptomatic carriers of HCV (13/39 or 33%). In seven patients with acute hepatitis C, IgM anti-CP14 continued to decrease in two in whom hepatitis resolved, but increased in five in whom hepatitis once resolved and then exacerbated. IgM anti-CP14 was followed in 30 patients with chronic hepatitis C during 24 weeks while they received recombinant interferon α-2a. IgM anti-CP14 decreased remarkably within 8 weeks in all of them. Thereafter, it continued to decrease in nine patients who responded to interferon and lost HCV RNA from circulation, but started to increase in five non-responders who continued to have high titers of HCV RNA. In the remaining 16 patients in whom HCV RNA decreased once and then increased, IgM anti-CP14 continued to decrease till 20 weeks and then increased. These results indicate that IgM anti-CP14 reflects the activity of liver disease, and is useful in following the outcome of patients with acute hepatitis C and in monitoring the response to interferon in patients with chronic hepatitis C. © 1994 Wiley-Liss, Inc.     

Hepatitis C viraemia rebound after "successful" interferon therapy in patients with chronic non-A, non-B hepatitis.

A quantitative polymerase chain reaction (PCR) assay for hepatitis C viral RNA (HCV-RNA) was used to monitor viraemia levels in six patients at multiple time points before, during, and after interferon therapy for chronic non-A, non-B hepatitis (NANBH). Prior to therapy, serum HCV-RNA was detected in all patients at approximately 10(4)-10(5) HCV genomes/ml. HCV viraemia became undetectable within 1 month of commencing interferon in three of the five patients whose alanine aminotransferase (ALT) levels decreased to normal on therapy. In the remaining two responder patients, viraemia levels declined more slowly, becoming undetectable after a period of several months. Recurrence of viraemia during therapy was observed in two cases. The one patient whose serum ALT levels remained elevated throughout therapy showed no decline in viraemia. On stopping interferon after a 6 months course, HCV genome titres climbed rapidly in all patients, reaching higher levels than had been observed prior to therapy. Biochemical relapse occurred within 7 months of ending interferon treatment in all but one of the patients who demonstrated this viraemia "rebound" phenomenon.     

Longitudinal study of hepatitis C viremia in chronic hepatitis C

Serial serum samples from 20 untreated patients with chronic hepatitis C virus (HCV) infection were tested for HCV RNA by a nested polymerase chain reaction assay using primers from the highly conserved 5′ noncoding region to determine the relationship between hepatitis C viremia and the activity of liver disease during the natural course of chronic HCV infection. Semiquantitation of serum HCV RNA level was achieved by testing serial 10-fold dilutions of RNA extracts to determine the end-point titer. All the patients were HCV RNA positive at presentation. There was a poor correlation between the initial HCV RNA titer and serum transaminase levels. All patients except one were persistently HCV RNA positive during a follow-up period of 1.5-15 years, although 17 (85%) had periods of normal or near-normal transaminase levels. There was no correlation between changes in the serum transaminase levels and HCV RNA titer. Patients with chronic HCV infection have persistent viremia despite fluctuations in ALT levels.     

小儿慢性丙型肝炎外周血T细胞亚群和TH1/TH2型细胞因子的研究

目的通过研究小儿慢性丙型肝炎外周血T细胞亚群及TH1/TH2型细胞因子的表达,进一步探讨小儿慢性丙型肝炎的免疫发病机制。方法(1)流式细胞仪(FACS)检测16例慢性丙型肝炎患儿及10例正常对照外周血T细胞亚群。(2)将慢性丙型肝炎患儿和正常对照外周血单个核细胞(PBMC)体外培养72h后,用ELISA法检测培养上清中TH1型细胞因子(IFN-γ、IL-2、IL-12和TNF-γ)和TH2型细胞因子(IL-4、IL-10)的浓度。结果(1)CD4 细胞无明显变化。CD8 细胞与正常对照比较明显升高(P<0.05)。CD3 细胞升高,CD4 /CD8 比值下降,但与正常对照比较无统计学意义(P>0.05)。(2)PBMC培养上清中IFN-γ、IL-10和TNF-α的水平明显升高(P<0.01),而没有检测到IL-2、IL-4、IL-12的基础分泌。结论慢性丙型肝炎患儿体内T淋巴细胞存在数量和功能的异常,CD8 细胞数升高,CD4 细胞功能异常,表现在以TH2型细胞因子的分泌为主。这可能与丙肝病毒(HCV)感染的慢性化有关。     

Induction of potent cellular immune response in mice by hepatitis C virus NS3 protein with double-stranded RNA

Double-stranded RNA is produced during virus replication and, together with the viral antigen, is responsible for inducing host antivirus immunity. The hepatitis C virus (HCV) non-structural protein-3 (NS3) has been implicated in the immune evasion of HCV, and is one of the prime targets for inducing immunity against HCV infection. Mice were immunized with recombinant NS3 protein (rNS3) and poly (I:C) emulsified in Montanide ISA 720 (M720). Cytokine production was assayed by enzyme-linked immunospot assay, and CD4(+) IFN-gamma(+) T helper (Th) cells or CD8(+) IFN-gamma(+) cytotoxic T lymphocytes were detected by flow cytometry. Anti-NS3 titre and immunoglobulin G2a (IgG2a) and IgG1 levels were monitored by enzyme-linked immunosorbent assay. Administration of rNS3 formulated in poly (I:C) and M720 induced anti-NS3 titres with a predominantly IgG2a isotype comparable to those induced by rNS3 in CpG-ODN and M720. The cytokine profiles showed that this formulation induced a Th1-biased immune response with several-fold more interferon-gamma (IFN-gamma)-producing cells than interleukin-4-producing cells. In contrast, rNS3 in M720 induced a Th2-biased immune response. The frequency of IFN-gamma-producing CD4(+) and CD8(+) cells induced by rNS3 in poly (I:C) and M720 was significantly higher than that induced by rNS3, rNS3 in M720, or rNS3 in poly (I:C), and was comparable to that induced by rNS3 in CpG-ODN with M720. The antigen-specific CD8(+) T-cell immune response persisted for up to 7 months after immunization. In conclusion, poly (I:C) with rNS3 in M720 can elicit a strong and persistent Th1-biased immune response and a cytotoxic T-lymphocyte response through cross-priming in mice. This study highlighted a promising formulation for inducing an efficient cellular immune response against HCV that has potential for HCV vaccine development.