title: Efficient class II major histocompatibility complex presentation of endogenously synthesized hepatitis C virus core protein by Epstein-Barr virus-transformed B-lymphoblastoid cell lines to CD4(+) T cells.
abstract: The induction of an efficient CD4(+) T-cell response against hepatitis C virus (HCV) is critical for control of the chronicity of HCV infection. The ability of HCV structural protein endogenously expressed in an antigen-presenting cell (APC) to be presented by class II major histocompatibility complex molecules to CD4(+) T cells was investigated by in vitro culture analyses using HCV core-specific T-cell lines and autologous Epstein-Barr virus-transformed B-lymphoblastoid cell lines (B-LCLs) expressing structural HCV antigens. The T- and B-cell lines were generated from peripheral blood mononuclear cells derived from HCV-infected patients. Expression and intracellular localization of core protein in transfected cells were determined by immunoblotting and immunofluorescence. By stimulation with autologous B-LCLs expressing viral antigens, strong T-cell proliferative responses were induced in two of three patients, while no substantial stimulatory effects were produced by B-LCLs expressing a control protein (chloramphenicol acetyltransferase) or by B-LCLs alone. The results showed that transfected B cells presented mainly endogenously synthesized core peptides. Presentation of secreted antigens from adjacent antigen-expressing cells was not enough to stimulate a core-specific T-cell response. Only weak T-cell proliferative responses were generated by stimulation with B-LCLs that had been pulsed beforehand with at least a 10-fold-higher amount of transfected COS cells in the form of cell lysate, suggesting that presentation of antigens released from dead cells in the B-LCL cultures had a minimal role. Titrating numbers of APCs, we showed that as few as 10(4) transfected B-LCL APCs were sufficient to stimulate T cells. This presentation pathway was found to be leupeptin sensitive, and it can be blocked by antibody to HLA class II (DR). In addition, expression of a costimulatory signal by B7/BB1 on B cells was essential for T-cell activation.
authors.affiliation: Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan. m.chen@mci2000.com
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Shirai
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: T
authors.initials: T
authors.lastname: Arichi
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Nishioka
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D019556:COS Cells; D002455:Cell Division / Q000276:immunology; D002461:Cell Line, Transformed; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D005814:Genes, Viral; D004854:Herpesvirus 4, Human / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007976:Leupeptins / Q000276:immunology; D014758:Viral Core Proteins / Q000276:immunology*; D015678:Viral Structural Proteins / Q000235:genetics
chemical_list: D000949:Histocompatibility Antigens Class II; D007976:Leupeptins; D014758:Viral Core Proteins; D015678:Viral Structural Proteins; C069130:nucleocapsid protein, Hepatitis C virus; D015500:Chloramphenicol O-Acetyltransferase; C032854:leupeptin