The natural history of acute hepatitis C: clinical presentation, laboratory findings and treatment outcomes

BACKGROUND

Acute hepatitis C has variable modes of presentation and frequently results in chronic infection. Its optimal management has yet to be defined.

AIM

To establish natural history and complications of treatment of acute hepatitis C.

METHODS

Data from all patients presenting with acute hepatitis C to the National Institutes of Health between 1994 and 2007 were reviewed.

RESULTS

Twenty-five patients were identified. Symptoms were reported by 80% and jaundice by 40%. Aminotransferase levels and hepatitis C virus (HCV) RNA levels fluctuated greatly; 18% of patients were intermittently negative for HCV RNA. Five patients recovered spontaneously whereas 20 developed chronicity or received interferon-based therapy during the acute phase. Among 15 patients treated during the acute phase with peginterferon with or without ribavirin for 24 weeks, all became HCV RNA negative within 4-8 weeks, and all except two (HIV-positive) achieved a sustained virological response. Side effects (particularly psychiatric) were common and limited treatment in 30%.

CONCLUSIONS

Among 25 patients with acute HCV infection, fluctuating illness was common and spontaneous recovery occurred in only 20%. Anti-viral treatment with a 24-week course of peginterferon and ribavirin was highly effective, but marked by frequent and severe side effects.

The natural history of acute hepatitis C: clinical presentation, laboratory findings and treatment outcomes

BACKGROUND

Acute hepatitis C has variable modes of presentation and frequently results in chronic infection. Its optimal management has yet to be defined.

AIM

To establish natural history and complications of treatment of acute hepatitis C.

METHODS

Data from all patients presenting with acute hepatitis C to the National Institutes of Health between 1994 and 2007 were reviewed.

RESULTS

Twenty-five patients were identified. Symptoms were reported by 80% and jaundice by 40%. Aminotransferase levels and hepatitis C virus (HCV) RNA levels fluctuated greatly; 18% of patients were intermittently negative for HCV RNA. Five patients recovered spontaneously whereas 20 developed chronicity or received interferon-based therapy during the acute phase. Among 15 patients treated during the acute phase with peginterferon with or without ribavirin for 24 weeks, all became HCV RNA negative within 4-8 weeks, and all except two (HIV-positive) achieved a sustained virological response. Side effects (particularly psychiatric) were common and limited treatment in 30%.

CONCLUSIONS

Among 25 patients with acute HCV infection, fluctuating illness was common and spontaneous recovery occurred in only 20%. Anti-viral treatment with a 24-week course of peginterferon and ribavirin was highly effective, but marked by frequent and severe side effects.

Identification of a new Patr-B*01 variant, Patr-B*0102, by sequence-based typing in a chimpanzee (Pan troglodytes)

Description of a new non-human primate major histocompatibility complex (MHC)-B (Patr-B) allele.

Identification of new major histocompatibility complex-A, -B, -C alleles in chimpanzees (Pan troglodytes)

Two new Patr-A, five new Patr-B and three new Patr-C alleles from Pan troglodytes are described.

Description of two new major histocompatibility complex (MHC) class II DRB1 [Pan troglodytes (Patr)-DRB1] alleles

Sequence-based typing strategy is used to identify polymorphism of Patr-DRB1. Two new Patr-DRB1 are described.

Identification of four novel MHC-C alleles in chimpanzees

Sequence-based typing strategy is used to identify polymorphism of Patr-C. Four new Patr-C alleles are described.

Cross-reactivity between hepatitis C virus and Influenza A virus determinant-specific cytotoxic T cells

The cellular immune response contributes to viral clearance as well as to liver injury in acute and chronic hepatitis C virus (HCV) infection. An immunodominant determinant frequently recognized by liver-infiltrating and circulating CD8(+) T cells of HCV-infected patients is the HCV(NS3-1073) peptide CVNGVCWTV. Using a sensitive in vitro technique with HCV peptides and multiple cytokines, we were able to expand cytotoxic T cells specific for this determinant not only from the blood of 11 of 20 HCV-infected patients (55%) but also from the blood of 9 of 15 HCV-negative blood donors (60%), while a second HCV NS3 determinant was recognized only by HCV-infected patients and not by seronegative controls. The T-cell response of these healthy blood donors was mediated by memory T cells, which cross-reacted with a novel T-cell determinant of the A/PR/8/34 influenza A virus (IV) that is endogenously processed from the neuraminidase (NA) protein. Both the HCV NS3 and the IV NA peptide displayed a high degree of sequence homology, bound to the HLA-A2 molecule with high affinity, and were recognized by cytotoxic T lymphocytes with similar affinity (10(-8) M). Using the HLA-A2-transgenic mouse model, we then demonstrated directly that HCV-specific T cells could be induced in vivo by IV infection. Splenocytes harvested from IV-infected mice at the peak of the primary response (day 7 effector cells) or following complete recovery (day 21 memory cells) recognized the HCV NS3 peptide, lysed peptide-pulsed target cells, and produced gamma interferon. These results exemplify that host responses to an infectious agent are influenced by cross-reactive memory cells induced by past exposure to heterologous viruses, which could have important consequences for vaccine development.

Genetic immunization of wild-type and hepatitis C virus transgenic mice reveals a hierarchy of cellular immune response and tolerance induction against hepatitis C virus structural proteins

To study the effect of genetic immunization on transgenic expression of hepatitis C virus (HCV) proteins, we evaluated the immunological response of HCV transgenic mice to HCV expression plasmids. FVB/n transgenic mice expressing HCV structural proteins (core, E1, and E2) and wild-type (WT) FVB/n mice were immunized intramuscularly with plasmids expressing core (pHCVcore) or core/E1/E2 (pHCVSt). After immunization, HCV-specific humoral and cellular immune response was studied. Both WT and transgenic mice immunized with either HCV construct produced antibodies and exhibited T-cell proliferative responses against core or envelope. In WT mice immunized with pHCVSt, cytotoxic T-lymphocyte (CTL) activities were detected against E2 but not against core or E1, whereas strong CTL activities against core could be detected in WT mice immunized with pHCVcore. In pHCVSt-immunized, transgenic mice, CTL activities against the core or envelope were completely absent, but core-specific CTL activities could be detected in pHCVcore-immunized transgenic mice. A similar pattern of immune responses was also observed in other mouse strains, including a transgenic line expressing human HLA-A2.1 molecules (AAD mice). Despite the presence of a peripheral cellular immunity against HCV, no liver pathology or lymphocytic infiltrate was observed in these transgenic mice. Our study suggests a hierarchy of CTL response against the HCV structural proteins (E2 > core > E1) in vivo when the proteins are expressed as a polyprotein. The HCV transgenic mice can be induced by DNA immunization to generate anti-HCV antibodies and anticore CTLs. However, they are tolerant at the CTL level against the E2 protein despite DNA immunization.

Emergence of a distinct pattern of viral mutations in chimpanzees infected with a homogeneous inoculum of hepatitis C virus

BACKGROUND & AIMS

Prospective, long-term study of viral evolution and immunologic responses in chimpanzees infected with a homogeneous hepatitis C virus (HCV) population is crucial in understanding the pathogenesis of HCV-host interactions.

METHODS

A molecular clone was constructed of HCV genotype 1b and RNA transcribed from this clone inoculated intrahepatically into chimpanzee X0142. Serum was taken from X0142 at week 2 and inoculated intravenously into a second chimpanzee (X0234). Detailed virologic, serologic, and immunologic analyses of these 2 chimpanzees were performed.

RESULTS

Both chimpanzees developed persistent viremia, with titers of 10(3) to 10(5) genomes/mL, for 80 weeks (X0142) and 55 weeks (X0234) of follow-up. A late antibody response against the nonstructural proteins and a weak, transient T-helper proliferative response were detected in both animals. In X0142, 25 mutations emerged in the virus population by week 78 and 15 in X0234 by week 35. A relatively large proportion of mutations affecting protein sequences appeared in the NS5A gene (33% in X0142 and X0234 combined), and 5 mutations were common to both chimpanzees.

CONCLUSIONS

In this long-term study of the molecular evolution of HCV genotype 1b from a cloned source, the appearance of a distinct pattern of mutations is suggestive of an adaptive response of HCV in vivo. In addition, a limited virus-specific immunity may contribute to HCV persistence.

Oral immunization with HCV-NS3-transformed Salmonella: induction of HCV-specific CTL in a transgenic mouse model

BACKGROUND & AIMS

The ability to induce cytotoxic T cells is considered an important feature of a candidate hepatitis C virus (HCV) vaccine. We used an oral immunization strategy with attenuated HCV-NS3-transformed Salmonella typhimurium to deliver DNA directly to the gut-associated lymphoid tissue.

METHODS

HLA-A2.1 transgenic mice were immunized once with transformed attenuated Salmonella. HCV-specific CD8+ T cells were analyzed in vitro as well as in vivo by challenge of mice with recombinant HCV-NS3 vaccinia virus.

RESULTS

Salmonella (10(8) colony-forming units; 20 microg plasmid DNA) induced cytotoxic and IFN-gamma-producing CD8+ T cells specific for the immunodominant epitope NS3-1073 in 26 of 30 mice (86%) that persisted for at least 10 months. A second epitope (NS3-1169) was also recognized by cytotoxic and IFN-gamma-producing T cells, whereas a third one (NS3-1406) stimulated IFN-gamma production without cytotoxicity. The minimal amount of plasmid DNA required to induce CTLs was 2 ng. Upon challenge with recombinant HCV-NS3-expressing vaccinia virus, vaccinia titers were significantly lower in mice immunized with Salmonella-NS3 than in mice immunized with control Salmonella, demonstrating the in vivo function of CTLs.

CONCLUSIONS

Oral immunization with attenuated Salmonella typhimurium as a carrier for HCV DNA induces long-lasting T-cell responses.

Direct functional analysis of epitope-specific CD8+ T cells in peripheral blood

The functional status of virus-specific CD8+ T cells is important for the outcome and the immunopathogenesis of viral infections. We have developed an assay for the direct functional analysis of antigen-specific CD8+ T cells, which does not require prolonged in vitro cultivation and amplification of T cells. Whole blood samples were incubated with peptide antigens for <5 h, followed by staining with peptide-MHC tetramers to identify epitope-specific T cells. The cells were also stained for the activation marker CD69 or for the production of cytokines such as interferon-gamma (IFNgamma) or tumor necrosis factor-alpha (TNFalpha). With the combined staining with tetramer and antibodies to CD69 or cytokines the number of antigen-specific CD8+ T cells as well as the functional response of each individual cell to the cognate antigen can be determined in a single experiment. Virus-specific CD8+ T cells that are nonfunctional, as well as those that are functional under the same stimulating conditions can be simultaneously detected with this assay, which is not possible by using other T-cell functional assays including cytotoxicity assay, intracellular cytokine staining, and enzyme-linked immunospot (ELISPOT) assay.

Mechanisms of alcoholic liver disease: cytokines

This article represents the proceedings of a workshop at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Manuela G. Neuman. The presentations were (1) New aspects of hepatic fibrosis, by D. A. Brenner; (2) Cellular immune response in hepatitis C models, by B. Rehermann; (3) The role of interleukin-10 in acute alcoholic hepatitis, by J. Taieb, S. Chollet-Martin, M. Cohard, J. J. Garaud, and T. Poynard; (4) Cytokine-mediated apoptosis in vitro, by M. G. Neuman; (5) Signaling for apoptosis and repair in vitro, by G. G. Katz, R. G. Cameron, N. H. Shear, and M. G. Neuman; (6) Interferons activate the P42/44 mitogen-activated protein kinase and Janus Kinase signal transducers and activation of transcription (JAK-STAT) signaling pathways in hepatocytes: Differential regulation by acute ethanol via a protein kinase C-dependent mechanism, by B. Gao; (7) Genetic polymorphisms of interleukin-1 in association with the development of Japanese alcoholic liver disease, by M. Takamatsu, M. Yamauchi, M. Ohata, S. Saito, S. Maeyama, T. Uchikoshi, and G. Toda; and (8) Increased levels of macrophage migration inhibitory factor in sera from patients with alcoholic liver diseases, by T. Kumagi, S. M. F. Akbar, M. Abe, K. Michitaka, N. Horiike, and M. Onji.

Interaction between the hepatitis C virus and the immune system

The hepatitis C virus (HCV) causes a wide spectrum of liver diseases ranging from symptomatic or asymptomatic acute infection with self-limited disease to persistent infection with chronic active hepatitis and an increased risk of liver cirrhosis and hepatocellular carcinoma. The outcome of HCV infection (i.e., viral clearance or persistence) and the manifestation and degree of liver disease is the result of complicated interactions between the virus and the immune response of the host. Remarkably, most de novo HCV infections are clinically inapparent and characterized by a high incidence (70%) of chronically evolving hepatitis, which suggests that HCV may have evolved strategies to not induce, overcome, or evade efficient immune responses of the host. This may be a multifactorial process, influenced by viral tissue tropism, replication, sequence variation and by functional alteration of infected cells. The interaction between HCV and the specific humoral and cellular immune response of the host, the role of the liver as the primary site of viral replication, the target of the host's immune response, and potential mechanisms of viral escape are discussed.

Cellular immune responses persist and humoral responses decrease two decades after recovery from a single-source outbreak of hepatitis C

As acute hepatitis C virus (HCV) infection is clinically inapparent in most cases, the immunologic correlates of recovery are not well defined. The cellular immune response is thought to contribute to the elimination of HCV-infected cells and a strong HCV-specific T-helper-cell (Th) response is associated with recovery from acute hepatitis C (ref. 2). However, diagnosis of resolved hepatitis C is based at present on the detection of HCV-specific antibodies and the absence of detectable HCV RNA, and detailed comparison of the humoral and cellular immune response has been hampered by the fact that patient cohorts as well as HCV strains are usually heterogeneous and that clinical data from acute-phase and long-term follow-up after infection generally are not available. We studied a cohort of women accidentally exposed to the same HCV strain of known sequence and found that circulating HCV-specific antibodies were undetectable in many patients 18-20 years after recovery, whereas HCV-specific helper and cytotoxic T-cell responses with an interferon (IFN)-gamma-producing (Tc1) phenotype persisted. The data indicate these HCV-specific CD4 + and CD8+ T cells are biomarkers for a prior HCV exposure and recovery. Because of undetectable antibodies against HCV, the incidence of self-limited HCV infections and recovery may be underestimated in the general population.

Pathogenesis, natural history, treatment, and prevention of hepatitis C

Approximately 4 million persons in the United States and probably more than 100 million persons worldwide are infected with hepatitis C virus. The virus has the unique ability to cause persistent infection in susceptible hosts after parenteral or percutaneous transmission, and its underlying mechanisms are not well understood. The immunologic correlates of protection and viral clearance and the pathogenesis of liver injury are yet to be defined, but recent studies suggest the importance of cell-mediated immune responses. Although 70% to 80% of infected persons become chronic carriers, most have relatively mild disease with slow progression. However, chronic and progressive hepatitis C carries significant morbidity and mortality and is a major cause of cirrhosis, end-stage liver disease, and liver cancer. Development of an effective hepatitis C virus vaccine is not imminent, but recent advances in technology and basic knowledge of molecular virology and immunology have engendered novel approaches to the fundamental problems encountered in vaccine development. Current therapy for hepatitis C, although effective in some patients, is problematic and still evolving. Advances in modern biology and immunology promise new therapies for this important disease.

Cellular immune response to the hepatitis C virus

Hepatitis C virus (HCV) infection is most often clinically inapparent and rarely associated with symptoms of acute hepatitis. Most patients, however, fail to resolve the acute infection and proceed to develop chronic hepatitis with the risk of liver cirrhosis and hepatocellular carcinoma later in life. Since the kinetics of the earliest events of virus-host interaction are likely to determine the outcome of infection, research has focused on the characterization of the strength and kinetics of the antiviral immune response in different stages of disease. The identification of the immunological correlates of viral clearance is pivotal for the development of vaccines and efficient therapies.

Quantitative analysis of hepatitis C virus-specific CD8(+) T cells in peripheral blood and liver using peptide-MHC tetramers

It is believed that the hepatitis C virus (HCV)-specific CD8(+) cytotoxic T lymphocytes (CTLs) play a role in the development of liver cell injury and in the clearance of the virus. To develop a direct binding assay for HCV-specific CTLs, we generated two peptide-MHC tetramers by using the recombinant HLA A2.1 molecule and A2-restricted T cell epitopes of the HCV NS3 protein. With these reagents we are able to detect specific CD8(+) cells in the blood of 15 of 20 HLA-A2(+), HCV-infected patients, at a frequency ranging from 0.01% to 1.2% of peripheral CD8(+) T cells. Phenotypic analysis of these specific cells indicated that there is a significant variation in the expression of the CD45 isoforms and CD27 in different patients. A 6-hour incubation of one patient's blood with NS3 peptides resulted in the activation of the epitope-specific CD8(+) cells, as indicated by their expression of CD69 and IFN-gamma. We also detected NS3-specific CD8(+) T cells in the intrahepatic lymphocyte population isolated from liver biopsies of two HCV-infected patients. The frequency of these specific CD8(+) cells in the liver was 1-2%, at least 30-fold higher than in the peripheral blood. All of the intrahepatic NS3-specific CD8(+) T cells were CD69(+), suggesting that they were activated CTLs. Direct quantitation and characterization of HCV-specific CTLs should extend our understanding of the immunopathogenesis and the mechanism of clearance or persistence of HCV.

A rare case of bloody diarrhea: thrombosis of the V. mesenterica inferior following laparoscopic cholecystectomy

Laparoscopic cholecystectomy has become the standard treatment for symptomatic cholecystolithiasis. The most common complications, as current experiences show, are bleeding, bile duct injury and non-technical complications like pneumonia. In some individual cases ischemic lesions of bowel by injury or thrombosis of intestinal vessels are described. Here we report the rare case of intestinal venous thrombosis following laparoscopic cholecystectomy. The complication clinically appeared within 24 h after operation starting with bloody diarrhea and mimicking inflammatory bowel disease. The patient, a 41-year old man, was treated with high-dose heparin and could be discharged after 44 days without complaints. Coloscopy six months after the event showed a restitution ad integrum.

Immunological significance of cytotoxic T lymphocyte epitope variants in patients chronically infected by the hepatitis C virus

This study was performed to test the hypothesis that cytotoxic T lymphocyte (CTL) selection of hepatitis C virus (HCV) escape variants plays a role in HCV persistence. The peripheral blood CTL responsiveness of patients with well-established chronic hepatitis C to a panel of 10 prototype HCV peptides (genotype 1a) was compared with the corresponding sequences encoded by the infecting viruses in each patient. Variant viral peptide sequences were threefold more frequent in the presence of a CTL response than in its absence, and CTL responses were detected nearly twice as often in association with variant rather than with prototype viral peptide sequences. Furthermore, over half of the patients were infected with potential CTL escape variants that contained nonimmunogenic and noncross-reactive variant peptides many of which displayed reduced HLA-binding affinity. Surprisingly, follow up analysis over a period of up to 46 mo revealed that, in contrast to the relatively high frequency of escape variants initially observed, the subsequent emergence rate of CTL escape variants was very low. Interestingly, the one escape variant that was detected proved to be a CTL antagonist. Collectively, these observations suggest that CTL selection of epitope variants may have occurred in these patients before their entrance into the study and that it may have played a role in HCV persistence. The low apparent rate of ongoing CTL selection in chronically infected patients, however, suggests that if CTL escape occurs during HCV infection it is probably an early event.

[Rare initial manifestation and differential diagnosis of primary sclerosing cholangitis]

BACKGROUND

Primary sclerosing cholangitis is most often diagnosed in middle-aged men who are suffering from inflammatory bowel diseases.

CASE REPORT

A young, previously healthy woman presents with icterus of acute onset, high transaminases and positive hepatitis B virus serology. Ultrasound and nuclear magnetic resonance images demonstrate multiple liver tumors. After acute viral hepatitis as well as primary or secondary malignant liver tumors have been excluded as underlying diseases, diagnosis of primary sclerosing cholangitis is made.

CONCLUSION

Differential diagnosis of primary sclerosing cholangitis should also be considered in cases with untypical primary presentation.

Immunopathology of hepatitis C

Hepatitis C virus (HCV) infection becomes persistent in the majority of instances in the face of a humoral and cellular immune response, and persistent HCV infection is associated with chronic hepatitis. In particular, cytotoxic T lymphocytes (CTL), crucial in the eradication of virus-infected cells, have been observed in the liver and the peripheral blood of chronically infected patients, suggesting that CTL cannot completely eliminate the virus, and may contribute to chronic liver injury. In this review, the potential host and the viral factors involved in the pathogenesis of chronic HCV infection will be discussed with emphasis on the HLA-A2 restricted peripheral blood CTL response and its relationship to liver disease and viral load.

Differential cytotoxic T-lymphocyte responsiveness to the hepatitis B and C viruses in chronically infected patients

Cytotoxic T lymphocytes (CTL) are thought to control hepatitis B virus (HBV) infection, since they are readily detectable in patients who clear the virus whereas they are hard to detect during chronic HBV infection. In chronic hepatitis C virus (HCV) infection, however, the virus persists in the face of a CTL response. Indeed, most infected patients respond to one or more HCV-1 (genotype 1a)-derived CTL epitopes in the core, NS3, and NS4 proteins, and the CTL response is equally strong in patients infected by different HCV genotypes, suggesting broad cross-reactivity. To examine the effect of the HCV-specific CTL response in patients with chronic hepatitis C on viral load and disease activity, we quantitated the strength of the multispecific CTL response against 10 independent epitopes within the HCV polyprotein. We could not detect a linear correlation between the CTL response and viral load or disease activity in these patients. However, the CTL response was stronger in the subgroup of patients whose HCV RNA was below the detection threshold of the HCV branched- chain DNA assay than in branched-chain-DNA-positive patients. These results suggest that the HCV-specific CTL response may be able to control viral load to some extent in chronically infected patients, and they indicate that prospective studies in acutely infected patients who successfully clear HCV should be performed to more precisely define the relationship between CTL responsiveness, viral clearance, and disease severity in this infection.

The hepatitis B virus persists for decades after patients' recovery from acute viral hepatitis despite active maintenance of a cytotoxic T-lymphocyte response

It is widely believed that the hepatitis B virus (HBV) is completely cleared by antiviral antibodies and specific cytotoxic T lymphocytes (CTLs) during acute viral hepatitis. We now demonstrate that traces of HBV are often detectable in the blood for many years after clinical recovery from acute hepatitis, despite the presence of serum antibodies and HBV-specific CTLs, which can be present at acute-stage levels. The strength of the CTL response to HBV following clinical recovery correlates with persistence of HBV DNA. It is of particular interest that HBV-specific CTLs from patients studied up to 23 years after clinical and serological recovery expressed activation markers (HLA-DR, CD69) indicating recent contact with antigen. These results suggest that sterilizing immunity to HBV frequently fails to occur after recovery from acute hepatitis and that traces of virus can maintain the CTL response for decades following clinical recovery, apparently creating a negative feedback loop that keeps the virus under control, perhaps for life.

Quantitative analysis of the peripheral blood cytotoxic T lymphocyte response in patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) are present in the peripheral blood and liver of chronically infected patients. The current study was performed to study the relationship between the strength of the CTL response, liver disease severity, and viral load. The results may be summarized as follows: first, using CTL precursor frequency (CTLpf) analysis to quantitate the peripheral blood CTL response, chronically infected patients were less strongly sensitized to a panel of well-defined HCV epitopes than they were to an epitope within the influenza matrix protein. Second, HCV-specific CTLpf did not correlate with disease activity or viral load in the majority of patients on a cross-sectional basis, although it did increase in three patients concomitant with sharp increases in liver disease. Finally, interferon therapy did not enhance the CTLpf against the HCV epitopes studied in these patients, indicating that its antiviral effect is independent of the CTL response. Since the HCV-specific CTLpf in the blood is actually quite low, the CTL may contribute to ongoing liver disease in these patients while being quantitatively inadequate to destroy all of the infected hepatocytes, thereby facilitating HCV persistence and contributing to chronic liver disease.

Immunopathogenesis of viral hepatitis

More than 500 million people world-wide suffer from viral hepatitis which can be caused by a variety of distinct infectious agents. The spectrum of disease, which ranges from acute self-limited hepatitis to liver cirrhosis, not only reflects the different biological properties and pathogenicity of the hepatitis viruses, but is also the result of the specific interaction between each virus and the immune system of the infected host. The immune response plays a crucial role in the elimination of the infecting virus as well as in disease pathogenesis and is described in detail for acute and chronic hepatitis B and C virus infection. Acute hepatitis B virus infection is characterized by a vigorous, polyclonal cytotoxic T lymphocyte response against HBV that is not readily detectable in patients with chronic hepatitis B, suggesting that resolution of disease is mediated by the HBV-specific CTL response in these patients. Because traces of virus as well as HBV-specific CTL can persist for decades after clinical recovery, continuous priming of new CTL by minute traces of virus is thought to protect from reactivation of disease. In contrast, the hepatitis C virus causes chronic liver disease despite a polyclonal and multispecific immune response, suggesting that distinct immunological and viral mechanisms determine the different clinical outcome of HBV and HCV infection. Their implications for the development of immunomodulatory vaccines to cure patients with chronic viral hepatitis are discussed.

Long-lasting memory T cell responses following self-limited acute hepatitis B

The molecular and cellular basis of long-term T cell memory against viral antigens is still largely undefined. To characterize anti-viral protection by memory T cells against non-cytopathic viruses able to cause acute self-limited and chronic infections, such as the hepatitis B virus (HBV), we studied HLA class II restricted responses against HBV structural antigens in 17 patients with acute hepatitis B, during the acute stage of infection and 2.2 to 13 yr after clinical resolution of disease. Results indicate that: (a) significant T cell proliferative responses to HBV nucleocapsid antigens were detectable in all patients during the acute phase of infection and in 14/17 also 2-13 yr after clinical resolution of disease; b) long-lasting T cell responses were sustained by CD45RO+T cells, predominantly expressing the phenotype of recently activated cells; c) limiting dilution analysis showed that in some patients the frequency of HBV-specific T cells was comparable to that observed in the acute stage of infection and, usually, higher than in patients with chronic HBV infection; d) the same amino acid sequences were recognized by T cells in the acute and recovery phases of infection; and e) HBV-DNA was detectable by nested-PCR in approximately half of the subjects. to conclusion, our results show that vigorous anti-viral T cell responses are detectable in vitro several years after clinical recovery from acute hepatitis B. Detection of minute amounts of virus in some recovered subjects suggests that long-term maintenance of an active anti-viral T cell response could be important not only for protection against reinfection but also for keeping the persisting virus under tight control.

Cytotoxic T lymphocyte responsiveness after resolution of chronic hepatitis B virus infection

Clearance of the hepatitis B virus (HBV) during acute hepatitis is associated with a strong, polyclonal, multispecific cytotoxic T lymphocyte (CTL) response to the viral envelope, nucleocapsid and polymerase proteins that persists for decades after clinical recovery. In contrast, chronically infected patients usually fail to mount a strong CTL response to this virus. In this study we demonstrate that chronically infected patients who experience a spontaneous or interferon-induced remission develop a CTL response to HBV that is similar in strength and specificity to patients who have recovered from acute hepatitis. The results suggest that specific immunotherapeutic enhancement of the CTL response to HBV should be possible in chronically infected patients, and that it could lead to viral clearance in these individuals with resolution of chronic liver disease.

Serological pattern of hepatitis C virus recurrence after liver transplantation

BACKGROUND/AIMS

Hepatitis C infection is characterized by a high incidence of liver cirrhosis, frequently requiring liver transplantation. After orthotopic liver transplantation, recurrence of hepatitis C virus infection is common, but often difficult to differentiate from allograft rejection. In this context the role and diagnostic value of hepatitis C virus-associated markers like the anti-GOR response have not yet been determined. In this study we analyzed the time course of hepatitis C virus recurrence in hepatitis C virus-infected patients who underwent liver transplantation because of end-stage cirrhosis or acute liver failure.

METHODS

We evaluated the serological pattern and diagnostic significance of anti-HCV, anti-HCV-IgM, anti-HCV-core, anti-HCV-core 5-27, anti-GOR, anti-GOR-IgM and HCV-RNA in serial serum samples during hepatitis C virus recurrence with or without allograft rejection up to 5-64 months after orthotopic liver transplantation. For comparison, we also studied these markers in serial serum samples from previously uninfected patients who acquired hepatitis C virus-infection during or shortly after orthotopic liver transplantation. Hepatitis C virus-infected patients who had undergone orthotopic liver transplantation were identified by screening pre-transplant sera from 235 patients for the presence of anti-HCV (2nd generation ELISA) and serum HCV-RNA (reverse transcription polymerase chain reaction).

RESULTS

Of 218 patients transplanted for end-stage liver cirrhosis, 65 (30%) were anti-HCV positive and 33 (15%) were HCV-RNA positive, while only one of 17 patients (6%) transplanted for acute liver failure was found to be anti-HCV positive without detectable HCV-RNA. Fifty-two hepatitis C virus-infected patients were studied serially before and after liver transplantation: 46 patients (89%) showed recurrent anti-HCV antibodies within 3 months and 51 patients (98%) within 42 months after orthotopic liver transplantation. Serum HCV-RNA was detected in 39 patients (75%) within 3 months and in 44 patients (85%) within 42 months after orthotopic liver transplantation. In the patients studied serially during hepatitis C virus-recurrence, anti-GOR antibodies displayed the same serological profile as hepatitis C virus antibodies, i.e. a decrease after orthotopic liver transplantation and slowly rising titers when HCV-RNA became detectable again. De novo infection with hepatitis C virus as studied in four patients produced a significant peak of anti-HCV titers accompanied or followed by an increase in anti-GOR titers, indicating that the immune response to GOR-autoantigen is triggered by the hepatitis C virus. No significant diagnostic difference between anti-GOR and anti-HCV was noted during hepatitis C virus recurrence and allograft rejection.

Hepatitis B virus (HBV) sequence variation of cytotoxic T lymphocyte epitopes is not common in patients with chronic HBV infection

It has been suggested that immune selection pressure exerted by the cytotoxic T lymphocyte (CTL) response could be responsible for viral persistence during chronic hepatitis B virus infection. To address this question, in the current study we compared the DNA and amino acid sequences of, and the CTL responses to, multiple HLA-A2-restricted CTL epitopes in the hepatitis B virus in several HLA-A2-positive patients with acute and chronic hepatitis. Our results indicate that the CTL response to these epitopes is barely detectable in the majority of patients with chronic hepatitis. Further, we show that the weak CTL response is not secondary in infection by mutant viruses lacking these epitopes, and we show that the CTL response did not select for escape mutants in any of these patients. We conclude that an ineffective hepatitis B virus specific CTL response is the primary determinant of viral persistence in chronic hepatitis and that immune selection of viral variants is not a common event in the majority of patients.

The cytotoxic T lymphocyte response to multiple hepatitis B virus polymerase epitopes during and after acute viral hepatitis

Cytotoxic T lymphocytes (CTL) are thought to contribute to viral clearance and liver cell injury during hepatitis B virus (HBV) infection. Using a strategy involving the in vitro stimulation of peripheral blood mononuclear cells (PBMC) with HBV-derived synthetic peptides containing HLA-A2.1, -A31, and -Aw68 binding motifs, we have previously described CTL responses to several epitopes within the HBV nucleocapsid and envelope antigens in patients with acute hepatitis. In this study we define six HLA-A2-restricted CTL epitopes located in the highly conserved reverse transcriptase and RNase H domains of the viral polymerase protein, and we show that the CTL response to polymerase is polyclonal, multispecific, and mediated by CD8+ T cells in patients with acute viral hepatitis, but that it is not detectable in patients with chronic HBV infection or uninfected healthy blood donors. Importantly, the peptide-activated CTL recognize target cells that express endogenously synthesized polymerase protein, suggesting that these peptides represent naturally processed viral epitopes. DNA sequence analysis of the viruses in patients who did not respond to peptide stimulation indicated that CTL nonresponsiveness was not due to infection by viral variants that differed in sequences from the synthetic peptides. CTL specific for one of the epitopes were unable to recognize several naturally occurring viral variants, except at high peptide concentration, underlining the HBV subtype specificity of this response. Furthermore, CTL responses against polymerase, core, and envelope epitopes were detectable for more than a year after complete clinical recovery and seroconversion, reflecting either the persistence of trace amounts of virus or the presence of long lived memory CTL in the absence of viral antigen. Finally, we demonstrated that wild type viral DNA and RNA can persist indefinitely, in trace quantities, in the serum and PBMC after complete clinical and serological recovery, despite a concomitant, vigorous, and sustained polyclonal CTL response. Since viral persistence is not due to escape from CTL recognition under these conditions, the data suggest that HBV may retreat into immunologically privileged sites from which it can seed the circulation and reach CTL-inaccessible tissues, thereby maintaining the CTL response in apparently cured individuals and, perhaps, prolonging the liver disease in patients with chronic hepatitis.

GOR-antibodies in patients with chronic liver disease and hepatocellular carcinoma

HCV infection frequently leads to liver cirrhosis and the development of hepatocellular carcinoma, while the mechanisms of carcinogenesis are still unclear. Autoantibodies like antinuclear antibodies have been described to increase and change their specificity in patients with hepatocellular carcinoma. Autoantibodies against GOR, an antigen not encoded by the viral but by the host's genome and overexpressed in tumor cells, are frequently associated with hepatitis C infection, but their significance during the development of hepatocellular carcinoma has not been determined yet. We analysed the frequency of GOR-antibodies in 38 patients with hepatocellular carcinoma on the grounds of liver cirrhosis of different origin, 38 patients with extrahepatic tumors, 24 patients with hepatitis C infection and 30 healthy controls. GOR-antibodies were found to be specifically associated with hepatitis C and were only found in patients with hepatocellular carcinoma if the liver cirrhosis was due to HCV-infection. Patients with extrahepatic tumors with or without liver metastasis had no detectable GOR antibodies, if no HCV infection was present. The determination of antibodies to the autoantigen GOR therefore has no clinical significance in patients with hepatic or extrahepatic tumors not related to HCV infection.

Gastroenterologic manifestations of mastocytosis

Mastocytosis as a rare disease is usually diagnosed by dermatologists because of urticaria pigmentosa as one of the leading signs. If the triad of urticaria pigmentosa, flush and diarrhea is present diagnosis is easily made. However, urticaria pigmentosa and flush may be less dominant or even absent and gastrointestinal signs may render diagnosis more difficult. Therefore, this review is thought to describe clinical manifestations of mastocytosis from the gastroenterologist's point of view. In addition, on the grounds of a recent classification of mastocytosis practical diagnostic procedures as well as therapeutic approaches are discussed.

Activation signals in human lymphocytes. Incorporation of polyunsaturated fatty acids into plasma membrane phospholipids regulates IL-2 synthesis via sustained activation of protein kinase C

Human PBL activated with anti-TCR/CD3 mAb express high affinity receptors for IL-2, synthesize IL-2, and subsequently proliferate. In contrast, lymphocytes activated by dioctanoylglycerol (DiC8) and ionomycin express high affinity receptors; however, no IL-2 synthesis is detectable. Anti-TCR/CD3 antibodies, as well as DiC8 cause translocation of protein kinase C (PKC) from the cytosol to the plasma membrane. In DiC8-stimulated cells translocation of PKC is detectable after 15 min, then it declines to control levels. In lymphocytes activated by antiTCR/CD3 mAb translocation of PKC is detectable after 15 min, then it declines to control levels, followed by a second, long lasting activation of the enzyme up to 4 h. Addition of polyunsaturated fatty acids to DiC8 + ionomycin-treated cells leads to IL-2 synthesis and proliferation. Incorporation of poly-unsaturated fatty acids into plasma membrane phospholipids results in long term activation of PKC. The results suggest that elevated incorporation of polyunsaturated fatty acids and thus continuous activation and translocation of PKC represents a necessary early signal for IL-2 synthesis and proliferation in human lymphocytes.

Activation signals in human lymphocytes. Incorporation of polyunsaturated fatty acids into plasma membrane phospholipids regulates IL-2 synthesis via sustained activation of protein kinase C

Human PBL activated with anti-TCR/CD3 mAb express high affinity receptors for IL-2, synthesize IL-2, and subsequently proliferate. In contrast, lymphocytes activated by dioctanoylglycerol (DiC8) and ionomycin express high affinity receptors; however, no IL-2 synthesis is detectable. Anti-TCR/CD3 antibodies, as well as DiC8 cause translocation of protein kinase C (PKC) from the cytosol to the plasma membrane. In DiC8-stimulated cells translocation of PKC is detectable after 15 min, then it declines to control levels. In lymphocytes activated by antiTCR/CD3 mAb translocation of PKC is detectable after 15 min, then it declines to control levels, followed by a second, long lasting activation of the enzyme up to 4 h. Addition of polyunsaturated fatty acids to DiC8 + ionomycin-treated cells leads to IL-2 synthesis and proliferation. Incorporation of poly-unsaturated fatty acids into plasma membrane phospholipids results in long term activation of PKC. The results suggest that elevated incorporation of polyunsaturated fatty acids and thus continuous activation and translocation of PKC represents a necessary early signal for IL-2 synthesis and proliferation in human lymphocytes.