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原贴由VirusIsNothing 发表于 2009-3-12 08:32
HBV（乙型肝炎病毒）特异性CTL（细胞毒T淋巴细胞）与旁观者（Bystander)非特异性CTL
象本医生一类所谓的健康、正常人（至少对HBV感染而言），感染乙肝病毒后，机体动用其免疫系统功能清除HBV的过程为一隐性过程，因此没有明显的临床表现和肝功能异常，亦不发展为慢性肝炎，更谈不上发展成乙肝后肝硬化和HBV相关性原发性肝细胞性肝癌。究其原因是机体针对HBV感染，产生了特异性抗HBV 免疫功能，即产生了有效的抗HBV的HBV特异性细胞毒T淋巴细胞（CTL）和B淋巴细胞，通过其相应的HBV特异性细胞毒活性（Cytotoxicity)，---清除病毒）和HBV特异性抗体（如抗HBS----防止再感染），有效地清除HBV而不损伤肝脏组织细胞，因此感染后没有明显的发病过程，而多在体检时是发现感染过HBV但已康复，此类情形在没有HBV感染家族史的国人中占95%左右，而有HBV感染家族史的国人中仅占5-10%。
对于急、慢性乙肝病人的比较研究发现，急性乙肝病人有明显的针对HBV的多位点、多克隆的强力CTL和CTL活性，而慢乙肝则相对低下，而所谓的"健康"" 正常""ＨＢＶ携带者则缺无。另外对肝功能和HBV复制状态各不相同的慢乙肝病人的免疫功能研究表明，有多位点和/或较强的HBV特异性细胞毒活性的病人其体内HBV复制不明显（受抑，HBV DNA阴性）而且肝功能正常，而缺乏多位点和/或较弱的HBV特异性细胞毒活性的病人其体内HBV复制明显（活跃，HBV DNA强阳性）而且肝功能明显异常，血清中炎性和抗炎细胞因子均明显上调，病人易于重症化或肝硬化或恶变。究其原因是机体如针对HBV感染，产生了一定的特异性抗HBV免疫功能，即产生了一定的抗HBV的HBV特异性细胞毒T淋巴细胞（CTL），通过其相应的HBV特异性细胞毒活性而抑制HBV复制，因此此一类病人HBV复制受抑/甚至转阴，而肝细胞没有损伤；但对于针对HBV感染，机体不能产生有效的特异性抗HBV免疫功能，即产生的抗HBV的HBV特异性细胞毒T淋巴细胞不是强力的、多位点和多克隆的，不能有效地通过其相应的HBV特异性细胞毒活性去抑制HBV复制，更谈不上清除HBV，而机体反馈性动用非特异性（旁观者、Bystander)细胞毒T淋巴细胞等免疫功能，通过炎性反应而产生大量有毒的氧自由基等对病毒和对人体组织细胞本身均有毒性的代谢产物，在抑制/清除病毒复制的同时，也对人体组织细胞本身造成损伤（主力/特种部队---HBV特异性CTL不力而非主力/特种部力---旁观者CTL“一哄而上”而产生诸多不是主力/特种部队所为的所作所为---付效应/组织损伤）。因此可以这么来说，机体感染时所产生的CTL越是具有最大的病原特异性（强力，全方位的多位点、多克隆），病原清除越是容易，其对机体损伤越是最小；反之，机体感染时所产生的CTL越是不具有病原特异性，激发非特异性炎症反应，病原基因突变而变异（毒力加强），病原越是不易被清除，而因所激发非特异性炎症反应造成的对机体损伤越是最大。
然而，想要产生强力，全方位的多位点、多克隆的HBV特异性的CTL和HBV特异性B淋巴细胞。以产生有效的HBV特异性细胞毒活性来清除病毒和产生HBV特异性抗体以防止HBV再感染，即建立HBV特异性细胞和体液免疫，就必须首先有赖于HBV特异性抗原提呈细胞（APC）的产生，即建立HBV特异性感应机制，即由感应细胞---APC“通知”效应细胞---CTL和B淋巴细胞，从而产生/建立HBV特异性细胞和体液免疫。
国外对丙肝研究发现，对干扰素完全有效者其APC功能多正常，而对干扰素无效的慢性丙肝则其APC功能低下。因此APC功能正常化对于慢性病毒性肝炎成功与否起决定性作用。
国内、外对病毒性肝癌研究发现，其APC功能明显低下，而且大量研究表明采用激活APC功能的APC疫苗技术对备种顽癌有治疗效果。
国外对HBV转基因小鼠研究表明，采用有效激活HBV特异性APC的APC疫苗疗法，肝脏免于受损的同时，小鼠血清和肝内HBV抗原和基因表达得以有效清除和抑制。
除HBS AG疫苗、乙肝特异性核糖核酸和转移因子是较为HBV特异性免疫疗法，目前的其他各种疗法包括干扰素免疫治疗等均为非HBV特异性疗法，主要是通过提高非特异性免疫功能来产生旁观者CTL，因此其治疗没有特异性，易于复发为其缺点，同时还或多或少有一定的促炎和损伤肝组织细胞等付作用。而HBS AG疫苗和乙肝特异性核糖核酸或转移因子虽为HBV特异性免疫疗法，但激活的免疫功能的作用点单一，而且强度不够强，因此疗效亦欠佳。
因此建立/恢复HBV特异性细胞与体液免疫是所谓的"健康""正常""ＨＢＶ携带者/慢性乙肝等HBV感染者的治疗关键所在，而建立/恢复HBV特异性细胞与体液免疫的前提是必须建立/恢复HBV特异性抗原提呈细胞（APC）及其APC功能。只有有效的HBV特异性抗原提呈细胞（APC）及其APC功能，才能产生有效的HBV特异性细胞与体液免疫，即“有什么样的干部，便有什么样的群众”，“上梁不正下梁歪”。
HVB特异性与非特异性免疫不同组合模式决定HBV感染者不同的预后（状态）模式
HBV感染后，激活机体免疫系统而发生相应的免疫反应，其中既有广泛的抗病毒、抗肿瘤的非特异性免疫反应，更有针对HBV的特异性免疫反应。
传统观点认为，HBV感染后机体免疫功能（特异性免疫）建立之时，便是HBV感染者出现临床症状、体征及肝功能异常时和病毒清除之时，即发病而表现为肝炎时。
然而，近二年，国外（英国和意大利等国医学研究人员）采用最新研究手段对HBV感染者进行了二个（急性肝炎和慢性肝炎）临床研究，发现：
1）对单一病毒株因自身疗法引起局部乙肝流行发病研究发现，在没有出现临床表现（症状、体征）和肝功能异常一月前，病人已出现了乙肝特异性免疫。虽然HBV DNA含量下降发生于肝功能异常出现之时，而HBV DNA含量下降至最低却出现于明显肝功能损伤前。急性肝炎病人除一例只有因其他病而必须使用糖皮质激素的病人因免疫受抑制而一直HBV复制指标阳性外，均完全转阴。说明乙肝特异性免疫与肝损伤没有关系，HBV清除与肝损伤（非特异免疫反应所致）没有直接关系。关于HBV清除与肝损伤关系，其实也可由版主等没有接种乙肝疫苗的正常人感染HBV后，没有明显临床表现和肝损伤而HBV复制指标自然转阴，而再次认证之。
GEORGE J. M. WEBSTER, STEPHANIE REIGNAT, MALA K. MAINI, SIMON A. WHALLEY, GRAHAM S. OGG, ABIGAIL KING, DAVID BROWN, PETER L. AMLOT, ROGER WILLIAMS, DIEGO VERGANI, GEOFFREY M. DUSHEIKO,1 AND ANTONIO BERTOLETTI.
Incubation Phase of Acute Hepatitis B in Man: Dynamic of Cellular Immune Mechanisms。
HEPATOLOGY 2000;32:1117-1124
After hepatitis B virus (HBV) infection, liver injury andviral control have een thought to result from lysis of in-fectedhepatocytes by virus-specific cytotoxic T cells. Pa-tientsare usually studied only after developing significantliver injury, and so the viral and immune events during theincubation phase of disease have not been defined. During asingle-source outbreak of HBV infection, we identified pa-tientsbefore the onset of symptomatic hepatitis. The dy-namicsof HBV replication, liver injury, and HBV-specificCD81 and CD41 cell responses were investigated fromincubation to recovery. Although a rise in alanine transam-inase(ALT) levels was present at the time of the initial fall inHBV-DNA levels, maximal reduction in virus level occurredbefore significant liver injury. Direct ex vivo quantificationof HBV-specific CD41 and CD81 cells, by using humanleukocyte antigen (HLA) class I tetramers and intracellularcytokine staining, showed that adaptive immune mecha-nismsare present during the incubation phase, at least 4weeks before symptoms. The results suggest that the pat-ternof reduction in HBV replication is not directly propor-tionalto tissue injury during acute hepatitis B in humans.Furthermore, because virus-specific immune responses and significant reductions in viral replication are seen during theincubation phase, it is likely that the immune events central to viral control occur before symptomatic disease.
Lohr HF, Krug S, Herr W, Weyer S, Schlaak J, Wolfel T, Gerken G, Meyer zum Buschenfelde KH.
Quantitative and functional analysis of core-specific T-helper cell and CTL activities in acute and chronic hepatitis B.
Liver 1998 Dec;18(6):405-13
AIMS/BACKGROUND: CD4+ T-helper cell (Th) responses to hepatitis B virus (HBV) core antigen (HBc) are increased during exacerbations in acute and chronic hepatitis B (AHB, CHB) and might influence the induction of CD8+ cytotoxic T lymphocytes (CTL) that are important for viral clearance.
METHODS: HBc-specific proliferative responses and cytokine release of blood mononuclear cells (PBMC) were studied in patients with AHB or CHB, as well as responders and non-responders to interferon-alpha treatment (IFN-R, IFN-NR), by [3H]-thymidine-uptake, enzyme-linked immunosorbent assay (ELISA) and Elispot assay and were compared to peptide HBc18 27-specific CTL precursor frequencies among CD8+ T cells derived from HLA-A2+ patients.
RESULTS: HBc-specific proliferative PBMC responses and Th frequencies were significantly increased in AHB patients compared with untreated CHB patients. PBMC derived from IFN-R showed stronger cellular responses than IFN-NR. Stimulated PBMC from all patient groups secreted significantly more IFN-gamma than IL-4 indicating Th1/Th0 cell responses. Furthermore, in AHB and IFN-R patients, high peptide HBc18-27-specific CTL precursor frequencies closely correlated with strong HBc-specific Th responses, whereas in untreated CHB and IFN-NR patients lower CTL frequencies were observed without correlation to Th activities.
CONCLUSIONS: HBV core-specific Th-cell responses appeared to support efficient CTL induction in patients with viral clearance, whereas in chronic HBV carriers quantitatively insufficient Th and CTL responses were observed. This observation could be important for future therapeutic strategies.
2）对慢性小三阳中二大类（肝功能正常和肝功能不正常）HBV感染者研究发现，肝功能正常病人（慢性肝炎静止期）有明显的HBV特异性免疫，肝内HBV特异性免疫的CD4+和CD8+T淋巴细胞多见，而肝功能不正常病人（慢性肝炎活动期）缺乏/没有HBV特异性免疫，肝内取而代之的是非特异性淋巴细胞和其他炎症细胞而致肝损伤。贺普丁治疗活动期慢乙肝发现使肝功能化同时，机体HBV特异性免疫功能恢复（原因是抗病毒复制后病毒抗原减少，而所受抑的免疫功能恢复）。此一研究再次表明，乙肝特异性免疫与肝损伤没有关系，HBV清除与肝损伤（非特异免疫反应所致）没有直接关系。
Maini MK, Boni C, Ogg GS, King AS, Reignat S, Lee CK, Larrubia JR, Webster GJ, McMichael AJ, Ferrari C, Williams R, Vergani D, Bertoletti A.
Direct ex vivo analysis of hepatitis B virus-specific CD8(+) T cells associated with the control of infection.
Gastroenterology 1999 Dec;117(6):1386-96
BACKGROUND & AIMS: Cytotoxic T cells have been suggested to be responsible for lysis of hepatitis B virus (HBV)-infected hepatocytes and control of virus infection. The frequency, kinetics, phenotype, and capacity for clonal expansion of circulating HBV-specific CD8 cells were analyzed directly in patients with acute HBV infection to clarify their pathogenetic role.
METHODS: Three HLA-A2 peptide tetramers able to visualize HBV core, envelope, and polymerase epitope-specific cytotoxic T lymphocytes were synthesized and used for flow cytometric analysis of antigen-specific populations.
RESULTS: Tetramer-positive cells specific for the core 18-27 epitope were found at a higher frequency than those specific for polymerase 575-583 and envelope 335-343 epitopes in most patients with acute HBV. The number of HBV-specific CD8 cells was highest during the clinically acute stage of infection and decreased after recovery. These cells expressed an activated phenotype and had an impaired capacity to expand in vitro and to display cytolytic activity in response to peptide stimulation. Recovery of these functions was observed when the frequency of specific CD8 cells decreased, coincident with a progressive decrease in their expression of activation markers.
CONCLUSIONS: This study provides the first ex vivo evidence that the highest frequency of circulating HBV-specific CD8 cells coincides with the clinically acute phase of hepatitis B. These cells exhibit an activated phenotype with limited further proliferative capacity that is restored during recovery.
Boni C, Penna A, Ogg GS, Bertoletti A, Pilli M, Cavallo C, Cavalli A, Urbani S, Boehme R, Panebianco R, Fiaccadori F, Ferrari C.
Lamivudine treatment can overcome cytotoxic T-cell hyporesponsiveness in chronic hepatitis B: new perspectives for immune therapy.
Hepatology 2001 Apr;33(4):963-71
The hepatitis B virus (HBV) cytotoxic T lymphocyte (CTL) response in patients with chronic HBV infection is generally weak or totally undetectable. This inability to mount protective CTL responses is believed to be a crucial determinant of viral persistence, and its correction represents an important objective of immune therapies for chronic hepatitis B. However, amplification of CTL responses in vivo may be ineffective if HBV-specific CD8 cells are either absent or nonresponsive to exogenous stimulation. In this study, we asked whether antiviral treatments able to inhibit viral replication and to reduce viral and antigen load can successfully reconstitute CTL responses creating the appropriate conditions for their therapeutic stimulation. For this purpose, the HBV-specific CTL response before and during lamivudine therapy was studied longitudinally in 6 HLA-A2-positive patients with HBeAg+ chronic hepatitis B. Both HBV-specific cytotoxic T cell activity measured by chromium release assay on peptide stimulation in vitro and CD8+ T cell frequency measured ex vivo by HLA-A2/peptide tetramer staining were significantly augmented by lamivudine therapy. This enhancement followed the reconstitution of CD4 reactivity and the decline of viral load induced by therapy. Our study shows that lamivudine treatment in chronic hepatitis B can restore CTL reactivity, making CTL susceptible to exogenous stimulation. This effect may enhance the probability that T cell-based immune therapies delivered after lamivudine treatment can successfully reconstitute a protective CTL response able to cure chronic HBV infection.
3）HVB特异性与非特异性免疫不同组合模式决定HBV感染者不同的预后模式
A）HVB特异性免疫合适+非特异性免疫无/低------》健康人隐性HBV感染而自然康复
B）HVB特异性免疫亚合适+非特异性免疫有（TH0、TH1）------》急性肝炎、重症肝炎
C）HVB特异性免疫无+非特异性免疫无------》健康HBV携带者
D）HVB特异性免疫低/无+非特异性免疫有（TH2、TH3）------》慢性肝炎、肝硬化
E）HVB特异性免疫低/无+非特异性免疫低下（NK和NK-T均低下）------》肝癌
Bertoletti A, Maini MK.
Protection or damage: a dual role for the virus-specific cytotoxic T lymphocyte response in hepatitis B and C infection?
Curr Opin Microbiol 2000 Aug;3(4):387-92
During infection with hepatitis B or C viruses, cytotoxic T lymphocytes (CTLs) have been implicated as both the mediators of protection and the principal effectors of liver pathology. Recent studies have allowed an investigation of the relationship between virus-specific CTL responses, liver damage and viral replication. In the presence of an efficient virus-specific CTL response, a scenario is emerging where inhibition of viral replication can be independent of liver pathology. We discuss the possibility that an inadequate CTL response--unable to control viral replication--may contribute to liver pathology not only directly but also via the recruitment of non-virus-specific T cells.
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发表于 2015-8-18 17:25:35
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