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.     

PREVALENCE OF HEPATITIS C VIRUS (HCV) COINFECTION IN HIV INFECTED INDIVIDUALS IN SOUTH INDIA AND CHARACTERIZATION OF HCV GENOTYPES

Purpose: To determine anti-HCV antibodies and genomic subtype of HCV in 1487 confirmed human immunodeficiency virus (HIV) positive samples. Methods: A total of 1487 confirmed HIV-positive samples were tested for anti-HCV antibodies by using a third generation ELISA kit (Ortho 3.0) and by RT PCR for HCV. HIV and HCV coinfected samples were selected for HCV genotyping by RFLP and subtyping with NS5-type specific primers. Results: A total of 1487 HIV-infected serum samples were screened for HCV infection, of which, a 1443 (97.04%) were negative and 45 (3.02%) were coinfected. HIV–HCV coinfection was predominant in the age group 41–50 years (51.1%). HCV genotyping and subtyping was done for the 45 HCV RNA-positive specimens of which genotype 1 was observed in 31 (68.8%) and genotype 3 was observed in 14 (31.1%) subjects. Further subtyping analysis showed the genotype 1b in 23 (51.1%), 1a in eight (17.7%), 3a in 10 (22.2%) and 3b in four (8.8%) subjects. Conclusion: HIV and HCV seroprevalence is higher in South India, and the most prevalent genotype in coinfection was genotype 1b.     

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.     

Lack of monomeric IgM anti-hepatitis C virus (HCV) core antibodies in patients with chronic HCV infection

Antibodies of the IgM class against the hepatitis C virus core antigen are found in up to 70% of patients with either acute or chronic hepatitis C. The sedimentation rate of such IgM was analyzed by rate-zonal centrifugation of nine sera taken from seven patients, two acutely and five persistently infected with hepatitis C virus. All patients had circulating high-molecular weight (i.e. pentameric) IgM, indicating that the production of low molecular weight IgM, commonly observed in other persistent viral infections, does not apply to hepatitis C virus and cannot be used to distinguish acute from chronic hepatitis C virus infection.     

RT-PCR检测肝炎和肝癌组织中的HCV复制中间体

应用逆转录聚合酶链反应(RT—PCR)检测11例血清抗HCV阳性的药瘾患者尸检肝组织和10例原发性肝细胞癌(PHC)患者手术切除肝癌组织中HCV基因(正链HCV RNA)和HCV复制中间体(负链HCV RNA)。结果8/11例肝组织和7/10例肝癌组织中正链HCV RNA阳性,其中各有6例负链HCV RNA亦阳性。HCV各基因区的检出率差别较大,5′NC区检出率最高、C区次之、NS区检出率较低。在同例肝(癌)组织中,若负链HCV RNA阳性,则其信号强度与正链基因无明显差别;但未发现肝癌组织中癌细胞分化程度与HCV的检出率有关。上述结果提示HCV感染与肝癌发生有密切关系,HCV的持续复制可能在癌肿形成中起作用。     

Detection of hepatitis C virus (HCV) proteins by immunofluorescence and HCV RNA genomic sequences by non-isotopic in situ hybridization in bone marrow and peripheral blood mononuclear cells of chronically HCV-infected patients

Immunofluorescence (IF) to detect HCV antigens and non-isotopic in situ hybridization (NISH) to detect HCV RNA genome were carried out on bone marrow (BM) and peripheral blood (PB) mononuclear cells (MC) of 11 chronically HCV-infected patients. In four patients (36·4%) HCV antigens were detected in monocytes/macrophages as well as in B lymphocytes in both BMMC and PBMC. Positive T lymphocytes in BMMC were found in three of them, but only one patient showed positive T cells in PBMC. NISH invariably demonstrated minus and plus HCV RNA genomic strands either in monocytes/macrophages or B and T lymphocytes in BMMC and PBMC in the four HCV antigen-positive patients and in two further patients not expressing viral proteins in blood MC. IF signals appeared diffusely distributed within the cytoplasm, or as brilliant granules in distinct submembrane areas or else in cytoplasm membrane. Nuclei never stained. Similarly, NISH displayed HCV RNA accumulation restricted to MC cytoplasm only, nuclei being persistently negative. NISH, however, was unable to detect cell membrane signal. Infection of blood MC is a common event in naturally acquired HCV infection, since none of these patients was conditioned by immunomodulating or immunosuppressive therapies. No difference was found in terms of mean age, length of disease, anti-HCV immune response, type and severity of chronic liver damage between patients with HCV-infected MC and patients without cell infection. These results demonstrate that HCV can infect BMMC and PBMC that represent important extrahepatic sites of virus replication, and may help to explain the immunological abnormalities observed in chronic HCV carriers.     

Virus-specific T-cell responses associated with hepatitis C virus (HCV) persistence in the liver after apparent recovery from HCV infection

Hepatitis C virus (HCV) RNA persistence in the liver has been described even after apparent resolution of HCV infection. Because T-cell reactivity plays a role in recovery from HCV infection, virus-specific T-cell responses were investigated in apparently recovered individuals in whom hepatic HCV RNA persistence was documented: 15 sustained virological responders to interferon (IFN)-treatment and 9 asymptomatic aviremic anti-HCV carriers. HCV-specific CD4(+) T-cell proliferative responses were detected significantly more often in apparently recovered individuals (sustained virological responders: 60%; asymptomatic anti-HCV carriers: 66%) compared with 50 chronic hepatitis C patients (28%; P < 0.05). However, T-cell frequencies and numbers tended to decline over time and the number of HCV proteins targeted by CD4(+) T-cell proliferative responses was limited. Interestingly, liver viral load correlated inversely with virus-specific immune responses. Thus, CD4(+) T-cell responders showed significantly lower hepatic HCV RNA levels (P < 0.05). HCV-specific IFN-gamma-secreting CD4(+) T-cells were not detected in all the apparently recovered patients although they were found significantly more often compared with chronic hepatitis C patients (P < 0.05). Also, HCV NS3-specific CD8(+) T-cells were detected in 11 HLA-A2-positive apparently recovered individuals (8 sustained virological responders and 3 asymptomatic anti-HCV carriers); T-cell frequencies tended to be greater in those patients who had lower hepatic viral levels. In conclusion, HCV-specific T-cells are detectable in apparently recovered individuals in whom HCV RNA can persist in the liver indicating that HCV replication may be prolonged in the face of an insufficient or inadequate virus-specific CD4(+) and CD8(+) T-cell response.     

Non‐neutralizing epitopes induce robust hepatitis C virus (HCV)‐specific antibody‐dependent CD56+ natural killer cell responses in chronic HCV‐infected patients

Natural killer (NK) cell‐mediated antibody‐dependent cellular cytotoxicity (NK‐ADCC) is of considerable interest in viral infection. However, little is known about NK‐ADCC responses in chronic hepatitis C virus (HCV) infection. In this study, impaired non‐specific antibody‐dependent CD56⁺ NK cell responses were observed in chronic HCV infection, as shown by decreased degranulation (extracellular CD107a expression) and interferon (IFN)‐γ production in response to antibody‐bound P815 cells. A peptide pool composed of epitopes recognized by anti‐HCV‐E1/E2 antibodies could induce pronounced HCV‐specific antibody‐dependent NK cell responses in sera from approximately half the chronic HCV carriers. Additionally, HCV‐specific epitopes with the capacity to induce robust NK‐ADCC activity were identified. Five linear NK‐ADCC epitopes (aa211‐aa217, aa384‐aa391, aa464‐aa475, aa544‐aa551 and aa648‐aa659 of the HCV envelope) were identified and do not overlap with putative linear neutralizing epitopes. This study revealed the dysfunctional characteristics of antibody‐dependent CD56⁺ NK cell responses in chronic HCV carriers. The key non‐neutralizing NK‐ADCC epitopes identified in this study may act as new targets for immunological intervention.