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Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human T cells that recognize a major epitope of the hepatitis B surface antigen were studied for their ability to react with antigen when presented by mouse fibroblasts that express class II products of the human major histocompatibility gene complex after gene transfection. L cells expressing HLA-DPw4, but not those expressing HLA-DR4 or HLA-DR7, induced strong proliferative responses of antigen-specific T cells to either hepatitis B surface antigen or the synthetic peptide S1d, which bears the immunodominant T-cell epitope. These results identified a genetic restriction element of human helper T-lymphocyte responses to a major antigenic determinant of hepatitis B virus and might be important in the design of subunit vaccines to this pathogen. Peptides that induce T-cell responses that are restricted by a frequently encountered major histocompatibility complex molecule in the general population such as DPw4 would be ideal candidates as subunit vaccines.
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PMID:Presentation of an immunodominant T-cell epitope of hepatitis B surface antigen by the HLA-DPw4 molecule. 246 81

In previous studies of the antibody response to hepatitis B vaccine in 598 subjects who received a full course of vaccination, we observed a bimodal response, with about 14 percent producing less than approximately 1000 radioimmunoassay (RIA) units. An analysis of the major histocompatibility complex (MHC) HLA and complement types of 20 of the subjects with the lowest responses indicated a greater-than-expected number of homozygotes for the extended or fixed MHC haplotype [HLA-B8, SC01, DR3]. This finding suggested that the lack of a normal response was a recessive MHC-linked trait. In this study, we prospectively vaccinated five homozygotes and nine heterozygotes for this haplotype in the expectation that the homozygotes would produce much lower levels of antibody than the heterozygotes. When the antibody response was assessed two months after the third injection, four of the five homozygotes had produced very low levels (approximately 1000 units or less) of antibody (mean, 467 RIA units; range, less than 8 to 1266), whereas all nine heterozygotes produced more than 2500 RIA units (mean, 15,608; range, 2655 to 28,900) (P less than 0.01). We conclude that the usual response to hepatitis B surface antigen is due to the presence of a dominant immune-response gene in the MHC and that a low response is due to the absence of such a gene and the presence on both chromosomes of MHC haplotypes (such as [HLA-B8, SC01, DR3]) that indicate such a response.
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PMID:Genetic prediction of nonresponse to hepatitis B vaccine. 213 97

In hepatitis B virus (HBV) infection correlation of disease activity with major histocompatibility complex (MHC) antigens has been suggested. However, no data are available regarding the nature and regulation of the immune response to the surface viral protein (HBsAg). This consideration and the current emphasis on production of an HBV vaccine led us to investigate the humoral immune response to HBsAg in inbred strains of mice to assess genetic factors that may regulate the humoral anti-HBs response. Studies with H-2 congenic and noncongenic inbred strains revealed the T-dependent humoral immune responses to the group-specific a and subtype-specific d determinants of HBsAg are regulated by gene(s) mapping to the murine MHC. The H-2q haplotype conferred high responsiveness, the H-2s,f haplotypes conferred low to nonresponsiveness, and the H-2a,b,d,k haplotypes were intermediate. Studies of H-2 recombinant strains allowed tentative mapping of regulation of the anti-a response and possibly the anti-d response to the K/I-A, I-B region of the MHC. The H-2-restricted regulation of the humoral immune response to HBsAg was circumvented by immunization with 10-fold higher HBsAg doses. These findings demonstrate a clear linkage between the murine MHC and the regulation of the immune response to specific determinants on HBsAg.
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PMID:Genetic regulation of the immune response to hepatitis B surface antigen (HBsAg). I. H-2 restriction of the murine humoral immune response to the a and d determinants of HBsAg. 617 55

Regulatory T-helper (Th) cells have been categorized into two functional subsets, Th1 and Th2 cells, which produce distinct lymphokines. In general, Th1 cells mediate cellular immune responses and Th2 cells mediate humoral immunity. Recent serological studies suggest that the Th1-Th2 balance may be relevant in acute and chronic hepatitis B virus (HBV) infections. The purpose of this study was to determine the potential of the nucleocapsid antigens (Ags) (hepatitis B core and e Ags [HBc/eAg]) of HBV to preferentially elicit either a Th1 or a Th2 dominant response. For this purpose, H-2 congenic B10.S and B10 mice were immunized with HBc/eAg, and Ag-specific T-cell proliferative responses, T-cell helper function, and T-cell cytokine production were analyzed. The results indicated that B10.S mice preferentially develop a Th1-like response whereas B10 mice preferentially develop a Th2-like response after immunization with HBc/eAg. Furthermore, the preferential Th1 and Th2 response patterns were reproduced when 12-residue peptides representing the dominant HBc/eAg-specific T-cell sites for B10.S (peptide 120-131) and B10 (peptide 129-140) mice were used as immunogens. Therefore, the combination of the T-cell site recognized and the major histocompatibility complex restricting element can in large part determine the Th phenotype of the HBc/eAg-specific T-cell response. Other factors that influenced Th phenotype were the presence of exogenous cytokines, Ag structure, and tissue distribution.
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PMID:Preferential recognition of hepatitis B nucleocapsid antigens by Th1 or Th2 cells is epitope and major histocompatibility complex dependent. 753 65

We investigated the major histocompatibility complex (MHC) class I-restricted presentation of an epitope of the hepatitis B virus small surface (S) antigen particle to cloned murine cytotoxic T lymphocytes (CTL). Efficient Ld-restricted presentation of the S28-39 epitope to CTL is observed in cells of different tissue origin pulsed in vitro, either with the antigenic S28-39 12-mer S-peptide, or with particulate S-antigen. The kinetics of epitope presentation differ in S-peptide-pulsed and in S-particle-pulsed cells: while a 15-min pulse with the antigenic peptide sensitizes targets for class I-restricted CTL lysis, presentation of S-particles requires 30-60 min to sensitize cells for CTL lysis. Uptake of antigenic material and active metabolism of the presenting cell are required for processing of S-particles, but not for sensitizing targets with S-peptides. Intracellular processing and presentation of S-particles is blocked in cells treated with chloroquine, NH4Cl, primaquine, or leupeptin, but not by treatment with cycloheximide or brefeldin A. This processing pathway operates efficiently in peptide-transporter-deficient, Ld-transfected T2 cells, revealing a novel endosomal/lysosomal processing pathway for class I-restricted presentation of peptides derived from exogenous S-particles.
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PMID:Hepatitis B virus small surface antigen particles are processed in a novel endosomal pathway for major histocompatibility complex class I-restricted epitope presentation. 753 71

Cellular immune responses to hepatitis B virus (HBV) play an important role in the resolution of acute infection. They also influence the course of chronic infection and disease but are inadequate to completely clear the infection. Woodchuck hepatitis virus (WHV) infection of the woodchuck can provide a model to study these processes. Lymphocyte responses of woodchucks were assessed by in vitro proliferation and/or interleukin (IL)-2 assays using mitogen (Concanavalin A [ConA]), cytokine (IL-2), superantigen (Staphylococcus aureus enterotoxin B [SEB]), major histocompatibility complex (MHC) allo-antigen (mixed lymphocyte reaction [MLR]), and viral antigens (woodchuck hepatitis virus core antigen [WHcAg] and woodchuck hepatitis virus surface antigen [WHsAg]). ConA-stimulated woodchuck lymphocytes underwent cell division based on cell counting experiments and produced IL-2 as detected using an IL-2-dependent murine cell line but failed to incorporate sufficient tritiated thymidine; however, they did incorporate sufficient tritiated adenosine and deoxyadenosine to permit development of a meaningful proliferation assay. The IL-2 assay was sensitive and specific for detection of woodchuck IL-2 induced by mitogen, superantigen, and MLR, as shown by quantitative titration analysis and anti-body neutralization of ConA-supernatant activity. Cyclosporin A and FK506 specifically inhibited ConA- and SEB-induced IL-2 production by woodchuck lymphocytes. Positive two-way MLRs were detected by IL-2 production and proliferation assay between woodchucks from different geographic regions, thus indicating divergence among MHC molecules; however, occasional negative MLR reactions among indigenous pairs of woodchucks indicated that some woodchucks were mutually immunocompatible to some degree. The radioadenosine proliferation assay was sensitive for detecting peripheral blood lymphocyte responses to WHcAg and WHsAg in adult woodchucks with recently resolved acute infections. The above systems should facilitate the design of adoptive therapy and liver transplantation experiments in the woodchuck, and also enable modeling of immune responses that promote and maintain chronic hepadnavirus infection.
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PMID:In vitro activation of woodchuck lymphocytes measured by radiopurine incorporation and interleukin-2 production: implications for modeling immunity and therapy in hepatitis B virus infection. 754 55

Identification of T-cell epitopes from foreign proteins is the current focus of much research. Methods using simple two or three position motifs have proved useful in epitope prediction for major histocompatibility complex (MHC) class I, but to date not for MHC class II molecules. We utilized data from pool sequence analysis of peptides eluted from two HLA-DR13 alleles to construct a computer algorithm for predicting the probability that a given sequence will be naturally processed and presented on these alleles. We assessed the ability of this method to predict known self-peptides from these DR-13 alleles, DRB1(*)1301 and *1302, as well as an immunodominant T-cell epitope. We also compared the predictions of this scoring procedure with the measured binding affinities of a panel of overlapping peptides from hepatitis B virus surface antigen. We concluded that this method may have wide application for the prediction of T-cell epitopes for both MHC class I and class II molecules.
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PMID:An empirical method for the prediction of T-cell epitopes. 759 Sep 73

Two class I major histocompatibility complex (MHC) proteins with molecular masses of 43- and 39-kDa were identified in the cell surface membranes of normal woodchucks using a newly developed antiwoodchuck class I monoclonal antibody (mAb) B1b.B9 and immunoblotting. B1b.B9 was generated by immunizing mice with viable woodchuck peripheral blood mononuclear cells and was selected for anti-class I MHC reactivity using a cellular enzyme-linked immunoassay, indirect immunofluorescence on tissue sections and flow cytofluorimetry. The distribution pattern of class I MHC antigen on woodchuck lymphoid cells was found to be similar to that reported in other species. Also, the antigen expression on normal woodchuck hepatocytes was comparable to that observed on normal human liver parenchymal cells; thus, the antigen was not detected on hepatocytes by staining of liver tissue sections, but was found by indirect immunofluorescence staining of isolated liver cells. Western blot analysis of the plasma membranes from normal woodchuck hepatocytes revealed the presence of a single species of class I MHC heavy chain protein with a molecular mass of 43-kDa, whereas splenocyte plasma membranes showed intense expression of a 43-kDa species, as well as the presence of a 39-kDa protein. The 39- and 43-kDa proteins were extracted with Triton X-114 to the hydrophobic protein phase, suggesting that they both contain a hydrophobic transmembrane domain. The data obtained indicate that the B1b.B9 identifies a nonpolymorphic epitope of woodchuck class I MHC heavy chains, providing an important reagent for the study of the pathogenesis of hepatitis B virus infection in a woodchuck model.
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PMID:Identification of woodchuck class I MHC antigens using monoclonal antibodies. 765 41

The hepatitis B virus (HBV) and polyomavirus (Py) enhancer regions contain multiple cis-acting elements that contribute to enhancer activity. The EF-C binding site was previously shown to be an important functional component of each enhancer region. EF-C is a ubiquitous binding activity that interacts with an inverted repeat sequence in the HBV and Py enhancer regions. Although the EF-C binding site is required for optimal enhancer function, the EF-C site does not possess intrinsic enhancer activity when assayed in the absence of flanking elements. With both the HBV and Py enhancer regions, EF-C stimulates the activity of adjacent enhancer elements in a synergistic manner. EF-C corresponds to RFX-1, a protein that binds to a conserved and functionally important site in major histocompatibility complex (MHC) class II antigen promoter regions. Interestingly, the RFX-1 binding site in MHC class II promoters only contains an EF-C half-site, maintaining one arm of the inverted repeat in an EF-C binding site. We have investigated the binding of purified EF-C and RFX-1 to sites in the Py and HBV enhancer regions that carry mutations that either disrupt one arm of the EF-C inverted repeat, or alter the spacing between the repeats. Our results show that the interaction of EF-C and RFX-1 with an intact inverted repeat is required for functional activity of these viral enhancer regions. Chemical footprinting and modification interference assays show that the interaction of EF-C and RFX-1 with the DRA MHC class II promoter truly represents half-site interaction, and that this binding is unstable. In contrast, the binding of EF-C and RFX-1 to the viral inverted repeats is stable. These results suggest that an additional activity may be required to stabilize EF-C/RFX-1 interaction with the MHC class II promoter, and that viral enhancer regions have evolved high affinity binding sites to sequester dimeric EF-C/RFX-1.
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PMID:Interaction of EF-C/RFX-1 with the inverted repeat of viral enhancer regions is required for transactivation. 771 44

The uses of GM-CSF as an immunomodulator and vaccine adjuvant are reviewed. GM-CSF has a variety of effects on immune responses: it induces class II major histocompatibility complex antigen expression on the surface of macrophages; it enhances dendritic cell maturation and migration; it results in a localized inflammation at the injection site; and it has marked effects on maturation of haematopoietic progenitor cells in the bone marrow. Animal and human studies suggest that administration of GM-CSF can increase antibody titres to foreign antigens. Monkeys injected with human interleukin (IL)-3 plus GM-CSF, at a different injection site, developed peak antibody titres which were 8- to 30-fold higher than those in monkeys injected with IL-3 alone. In a study of ovarian cancer patients receiving GM-CSF to prevent chemotherapy-induced neutropenia, two patients who had demonstrated a low titre of antithyroid antibodies prior to the study showed an increase in antibody titre and transient thyroiditis after administration of GM-CSF. Recently a GM-CSF/antigen fusion protein has been tested. An antibody corresponding to a specific idiotype expressed on B-cell lymphomas was fused to GM-CSF and injected into mice with B-cell lymphoma xenografts. The mice developed antibodies to the lymphoma and there was a protective effect against disease progression. Preliminary results of clinical trials using GM-CSF in humans suggest that it enhances antibody responses to hepatitis B vaccine. On the basis of these preliminary results, several clinical trials are being planned and it would appear that GM-CSF has potential as a vaccine adjuvant.
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PMID:Potential role of granulocyte-macrophage colony-stimulating factor as vaccine adjuvant. 787 53


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