title: Direct killing of Epstein-Barr virus (EBV)-infected B cells by CD4 T cells directed against the EBV lytic protein BHRF1.
abstract: Due to their low frequency, CD4 T-cell responses to Epstein-Barr virus (EBV) lytic antigens are, so far, poorly characterized. Human peptide major histocompatibility complex (MHC) class II multimers provide a means to detect and characterize such rare T cells. Along a screening of T-cell responses to lytic or latent EBV antigens within peripheral blood leukocyte (PBL)- or synovial-derived CD4 T-cell lines, we identified an human leukocyte antigen-DR*0401 (HLA-DR*0401)-restricted epitope derived from BHRF1 (BamHI fragment H rightward open reading frame 1), a viral protein produced during the early stages of the lytic cycle. We show here that T-cell responses to this particular BHRF1 epitope are shared by most EBV-infected DR*0401(+) individuals, as BHRF1-specific CD4 T cells could be sorted out from all the DRB*0401 T-cell lines analyzed, using magnetic beads coated with recombinant BHRF1/DR*0401 complexes. Sorting with these peptide MHC class II multimers was very efficient, as the yield of recovery of BHRF1-specific T cells was nearly 100%. Functional analysis of a large number of clones responding to BHRF1/DR*0401 demonstrated their cytolytic action against autologous and allogeneic DR*0401(+) EBV-transformed B-lymphoblastoid cell lines (B-LCLs), with 40% to 80% killing efficiency and potent interferon gamma production, thus suggesting that this CD4 T-cell population contributes to the control of EBV replication. B-LCL lysis by these T-cell clones was DR*0401 dependent, EBV dependent, and was not merely due to bystander killing. Taken together, these data provide the first demonstration that a lytic antigen can induce a direct cytolytic response against EBV-infected cells.
authors.affiliation: INSERM U463, Institut de Biologie, 9 quai Moncousu, 44035 Nantes Cedex 01, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Landais
authors.forename: Xavier
authors.initials: X
authors.lastname: Saulquin
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Scotet
authors.forename: Lydie
authors.initials: L
authors.lastname: Trautmann
authors.forename: Marie-Alix
authors.initials: MA
authors.lastname: Peyrat
authors.forename: John L
authors.initials: JL
authors.lastname: Yates
authors.forename: William W
authors.initials: WW
authors.lastname: Kwok
authors.forename: Marc
authors.initials: M
authors.lastname: Bonneville
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Houssaint
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002999:Clone Cells; D000939:Epitopes / Q000276:immunology; D020031:Epstein-Barr Virus Infections / Q000276:immunology*; D004854:Herpesvirus 4, Human / Q000254:growth & development*; D006801:Humans; D018189:Immunomagnetic Separation; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000378:metabolism; D018417:Th1 Cells / Q000166:cytology / Q000276:immunology; D014764:Viral Proteins / Q000276:immunology*; D014779:Virus Replication / Q000276:immunology
chemical_list: C083278:BHRF1 protein, Human herpesvirus 4; D000939:Epitopes; D014764:Viral Proteins; D007371:Interferon-gamma