Die Allokation bei Lebertransplantation (LTx) in der UNOS und EUROTRANSPLANT Region basiert auf dem Model for End-Stage Liver Disease (MELD) Score. Der MELD-Score wurde entwickelt, um die 3-Monats-Mortalität auf der Warteliste vorherzusagen – scheint jedoch suboptimal zur Vorhersage des Überlebens nach LTx. Der Wert anderer Scores: Donor-Risk-Index (DRI), Organ-Patient-Index (OPI) und der Balance-Of-Risk (BAR) Score – zur besseren Prädiktion des Outcomes muss noch evaluiert werden.

Background: Sofosbuvir (SOF) + ribavirin (RBV) for 12 or 24 weeks led to high SVR rates in genotype 2 or 3 HCV-infected patients, respectively, in the Phase 3 VALENCE study. We analyzed viral kinetics to determine the relationship to SVR12.

Haploidentical bone marrow transplantation with post-grafting cyclophosphamide: multicenter experience with an alternative salvage strategy

Introduction: Acute hepatitis C has become an infrequent disease in Europe. There is only limited data on disease severity in acute hepatitis C investigating more than 100 patients per study. We aimed to determine the role of BMI, sex and age in patients recruited for the German Hep-Net HCV treatment studies.

Die bisherigen Untersuchungsergebnisse zur HBV-Infektion zeigen, dass die akute selbstlimierte Viruselimination ist durch eine starke, gegen verschiedene Virusproteine gerichtet CD4+ und CD8+ T-Zellantwort gekennzeichnet ist, während für die chronische Infektion eine schwache oder nicht nachweisbare T-Zellreaktion typisch ist. Die Ursache hierfür unklar und schwierig zu untersuchen, da die Charakterisierung der CD4+-T-Zellantwort bisher ausschließlich über die Untersuchung der Effektorfunktionen möglich war. Mithilfe von HLA-Klasse-II-Tetrameren können nun erstmals viruspezifische Zellen unabhängig von der Funktion identifiziert werden. Um relevante HBV-core Epitope zu identifizieren, wurden PBMC von Patienten mit akuter HBV mit überlappenden HBV-core Peptiden stimuliert und ihre Aktivierung mittels H3-Proliferationsassays erfasst. Hierdurch wurden drei relevante HBV-core Epitope identifiziert, wobei für ein Epitop eine HLA-DR1-Restriktion nachgewiesen werden konnte. Durch den Einsatz von trunkierten Peptidvarianten wurde das Minimalepitop identifiziert, anhand welchem ein HLA-DRB*0101 Tetramer synthetisiert wurde. Die Spezifität dieses Tetramers konnte anhand eines korrespondierenden spezifischen CD4+ T-Zellklons gezeigt werden. In fünf HLA-DR1+ gesunden Kontrollpersonen und in fünf Patienten mit akuter HBV ohne HLA-DR1 Hintergrund konnten keine Tet+ Zellen nachgewiesen werden. Dagegen fanden sich in allen drei untersuchten HLA-DR1+ Patienten mit akuter HBV während der Peakphase Tet+ Zellen in einem Frequenzbereich von 900 bis 1680/106 CD4+ T-Zellen. Der Frequenzgipfel der Tet+ Zellen war mit dem GPT Gipfel und dem Gipfel der IFN-γ Sekretion assoziiert. In Patienten mit chronischer HBV Infektion zeigten sich keine oder nur sehr niedrige Tet+ Zellfrequenzen. Im Verlauf der akuten HBV zeigten sich deutliche Veränderungen bezüglich des Phänotyps der Tet+ CD4+ T-Zellen. Zusammenfassend ist es uns gelungen ein HBV-core HLA-Klasse-II-Tetramer zu etablieren und an drei HLA-DR1+ Patienten mit akuter HBV Verlaufsuntersuchungen bezüglich Frequenz und Phänotyp der Tet+ CD4+ T-Zellen durchzuführen. Die Anwendung dieses neuen Untersuchungswerkzeugs kann helfen, neue immunpathogenetische Mechanismen in der Entstehung einer chronischen HBV Infektion aufzudecken.

Einleitung: Die Dynamik von Mutationen in bekannten CD8 Epitopen und deren Einfluss auf die Immunantwort und den Erkrankungsverlauf in der Frühphase einer akuten Hepatitis C Virusinfektion ist bisher wenig untersucht.

Einleitung: Die CD4+ T Zellhilfe ist für die Aufrechterhaltung antiviraler Immunantworten von entscheidender Bedeutung. Auch konnte gezeigt werden, dass diese bei Patienten mit akuter Hepatitis C Infektion, die das Virus dauerhaft kontrollieren können, stark und lang anhaltend ist. Im Gegensatz hierzu ist sie bei Patienten mit chronischem Verlauf eher schwach oder gar nicht nachweisbar.

Eine Ausheilung der akuten Hepatitis C Infektion ist mit einer starken HCV-spezifischen CD4+ T-Zellantwort assoziiert, wohingegen diese bei einer chronisch verlaufenden Infektion meist fehlt oder nur transient vorhanden ist. Bisher stehen zur Analyse der CD4+ Immunantwort nur indirekte Methoden zur Verfügung. HCV-spezifische MHC-Klasse II Tetramere könnten ein neues Werkzeug darstellen, anhand welchem die immunologischen Mechanismen einer effektiven bzw. ineffektiven CD4+ T-Zellantwort besser analysiert werden können.

Hintergrund: Die plasmacytoiden dendritischen Zellen (pDC) sind neben ihrer Fähigkeit zur Antigenpräsentation die wesentlichen Interferon-alpha (IFN-α) Produzenten des Menschen. Da die HCV als auch die HBV Infektion erfolgreich mit IFN-α behandelt werden kann, ist die Beeinträchtigung der endogenen IFN-α Produktion als viraler Persistenzmechanismus vorstellbar.

We characterized the anti-viral T-cell response in 22 chronically infected patients, who participated in a European multi-center randomized placebo-controlled, double-blind study therapeutic vaccination trial with pre-S1, pre-S2 and S antigenic components of the hepatitis B virus (HBV). It induced a significant HBsAg-specific T-cell proliferation and the production of Th2-cytokines (i.e. IL-5). A specific induction of Th1-lymphokines was not detectable although this has been demonstrated in this study in response to the nucleocapsid protein (HBcAg). Further analysis indicated that this approach does not activate HBV-specific CD8+ T-lymphocytes as detected by ELISPOT-assay. Our results might explain why a specific therapeutic vaccine, although safe and well-tolerated is not always able to break tolerance leading to the clearance of the hepatitis B virus.

After infection by hepatitis C virus (HCV), a minority of patients develop acute symptomatic disease and some of them are able to clear the virus. In this study, we analyzed peripheral blood mononuclear cells from nine patients with acute symptomatic disease with respect to their cytotoxic T lymphocyte (CTL) response using a panel of HCV-derived peptides in a semiquantitative secondary in vitro culture system. We could detect early CTL responses in 67% of these patients. The CTL responses were directed against multiple viral epitopes, in particular within the structural (core 2-9, core 35-44, core 131-140, and core 178-187) and nonstructural regions of the virus (NS3 1073-1081, NS3 1406-1415, NS4 1807-1816, NS5 2252-2260, and NS5B 2794-2802). We compared the CTL responses displayed by recently and chronically infected HLA-A2-positive patients. Virus-specific CTLs were detectable in chronic carriers but the percentage of positive peptide-specific CTL responses was significantly higher in recently infected patients (P = 0.002). Follow-up of recently infected patients during subsequent disease development showed a significant decrease in the values and proportions of positive peptide-specific CTL responses (P = 0.002 and 0.013, respectively). Patients with limited viral replication exhibited significantly more vigorous early responses (P = 0.024). These data suggest a protective role for the early antiviral CTL response in HCV infection.

Background & Aims: Hepatitis B e antigen (HBeAg) and hepatitis B core antigen (HBcAg) seem to play different roles In the induction and regulation of the antiviral immune response, although the two antigens share all major CD4(+) T-cell epitopes, and these epitopes can be processed from both antigenes via the exogenous anti-gen-presenting pathway. The aim of this study was to test the ability of antigen-presenting cells to present epitopes from endogenously synthesized MBcAg/HBeAg on HLA class II molecules. Methods: Lymphoblastoid cell lines infected with recombinant vaccinia viruses containing various HBcAg or HBeAg constructs and stable transfectants Were tested for their ability to stimulate HBcAg/HBeAg-specific CD4(+) T-cell clones. Results: Only antigen-presenting cells infected with HBeAg constructs but not those infected with HBcAg constructs were able to stimulate HBcAg/HBeAg-specific CD4(+) T-cell clones. T-cell activation by HBeAg constructs was completely inhibited by brefeldin A but not affected by chloroquin. In contrast, T-cell activation by exogenous, recombinant HBcAg was inhibited by chloroquin but not by brefeldin A. Conclusions:The findings indicate that processing and HLA class II-associated presentation df endogenously synthesized HBeAg in virus-infected cells, including hepatocytes, may occur. This mechanism may be involved in the regulation of the CD4(+) T-cell response to HBcAg/HBeAg.

Cytokines that are secreted as a response to viral antigen not only have direct antiviral properties but also crucially influence immune reactions determining the outcome of infection. As an advantageous alternative to the study of cytokines present in the supernatants of antigen-specific T cell clones and lines, we have used ELISPOT assays to determine the number of interferon-gamma (IFN-gamma)- and IL4-producing cells generated by peripheral blood mononuclear cells from patients with acute hepatitis B (AHB) and chronic hepatitis B (CHB) infection in response to HBcAg in a short-term culture (48 h). In response to HBcAg IFN-gamma was predominantly produced. In contrast to the results obtained in acute hepatitis B, the typical lymphokine pattern in CHB was characterized by a weak or absent antigen-specific IFN-gamma production. A predominance of IL-4-producing cells was not observed in either AHB or CHB. A significant number of IFN-gamma-producing cells was usually detectable during phases of viral elimination and the quality of the lymphokine response seemed to be epitope independent. Comparison of the results obtained in proliferation assays and ELISPOT assays clearly shows that lymphokine production upon stimulation with viral protein is totally independent of T cell proliferation and more sensitively reflects antiviral reactivity.

T cells are believed to be the main players in antiviral defence. To investigate the role of the specific CD4+ T cell response for clearance and control of the hepatitis C virus we studied patients with acute hepatitis C (AHC) during the phase of spontaneous viral clearance and during follow up after elimination of the virus and resolution of disease. Symptomatic AHC has a self-limited course in 50% of patients, whereas the other half show virus persistence and develop chronic course of disease. Patients who were able to mount a vigorous, polyclonal, multispecific, TH1 lymphokine dominated CD4+ T-cell response showed viral clearance and a self-limited course of disease. In contrast, absence of this T-cell response in patients with AHC invariably led to viral persistence and chronic hepatitis. The characteristics of the T-cell response were as follows: it was mainly directed against nonstructural proteins of the virus, it was multispecific and demonstrated immunodominant epitopes, and the majority of T-cell clones established from our patients responded to a single peptide (NS3 amino acid 1248-1261) within the helicase region of HCV. Presentation of the peptide was HLA DR specific, the peptide showed promiscuous binding, and it had high binding affinity to 10 of the most common 13 HLA DR alleles, thus patients with diverse HLA DR backgrounds could mount an immune response. Furthermore, the epitope was conserved in 100% of 33 HCV strains published in databases. This strong initial CD4+ T-cell response is not sufficient for a definitive recovery from AHC, it has to be maintained to control the hepatitis C virus. Loss of the response after initial resolution of disease is followed by relapse. Even 20 years after an episode of self-limited AHC with elimination of HCV, we have observed a significant virus-specific CD4+ T-cell response. Our data indicate the decisive role of the virus-specific CD4+ T-cell response for clearance and control of HCV, and contribute to our understanding of immune mechanisms by which the host defends the HCV virus. This is a prerequisite for the development of new strategies to efficiently defend the virus by manipulating or modulating the immune response.

A strong virus-specific CD4+ and CD8+ T lymphocyte response to hepatitis B virus (HBV) has been associated with viral clearance, but little is known about factors determining the individual's ability to mount such a T cell response. Recently a strong association between the HLA class II allele DR13 and a self-limited course of HBV infection has been described. In the present study of 33 patients with acute hepatitis B we show that individuals carrying HLA-DR13 mount a more vigorous CD4+ T cell response to HBV core (5706 ct/min (25th/75th percentile 3239 ct/min; 10,552 ct/min)) than patients without HLA-DR 13 (1365 ct/min (490 ct/min; 5334 ct/min); P = 0.006). However, peptide epitopes aa 50-69, aa 61-85, and aa 81-105 were recognized most frequently by both patient groups. Moreover, among 14 HBV core-specific CD4+ T cell clones from two patients with HLA-DR13, only one T cell clone was HLA-DR13-restricted. Our data suggest that the beneficial effect of the HLA-DR13 alleles on the outcome of HBV infection could be explained by a more vigorous HBV core-specific CD4+ T cell response, which may either be due to more proficient antigen presentation by the HLA-DR13 molecules themselves or a linked polymorphism in a neighbouring immunoregulatory gene.