title: CD4+ T-cell responses to Epstein-Barr virus (EBV) latent-cycle antigens and the recognition of EBV-transformed lymphoblastoid cell lines.
abstract: There is considerable interest in the potential of Epstein-Barr virus (EBV) latent antigen-specific CD4+ T cells to act as direct effectors controlling EBV-induced B lymphoproliferations. Such activity would require direct CD4+ T-cell recognition of latently infected cells through epitopes derived from endogenously expressed viral proteins and presented on the target cell surface in association with HLA class II molecules. It is therefore important to know how often these conditions are met. Here we provide CD4+ epitope maps for four EBV nuclear antigens, EBNA1, -2, -3A, and -3C, and establish CD4+ T-cell clones against 12 representative epitopes. For each epitope we identify the relevant HLA class II restricting allele and determine the efficiency with which epitope-specific effectors recognize the autologous EBV-transformed B-lymphoblastoid cell line (LCL). The level of recognition measured by gamma interferon release was consistent among clones to the same epitope but varied between epitopes, with values ranging from 0 to 35% of the maximum seen against the epitope peptide-loaded LCL. These epitope-specific differences, also apparent in short-term cytotoxicity and longer-term outgrowth assays on LCL targets, did not relate to the identity of the source antigen and could not be explained by the different functional avidities of the CD4+ clones; rather, they appeared to reflect different levels of epitope display at the LCL surface. Thus, while CD4+ T-cell responses are detectable against many epitopes in EBV latent proteins, only a minority of these responses are likely to have therapeutic potential as effectors directly recognizing latently infected target cells.
authors.affiliation: CRUK Institute for Cancer Studies, The University of Birmingham, Vincent Dr., Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: H M
authors.initials: HM
authors.lastname: Long
authors.forename: T A
authors.initials: TA
authors.lastname: Haigh
authors.forename: N H
authors.initials: NH
authors.lastname: Gudgeon
authors.forename: A M
authors.initials: AM
authors.lastname: Leen
authors.forename: C-W
authors.initials: CW
authors.lastname: Tsang
authors.forename: J
authors.initials: J
authors.lastname: Brooks
authors.forename: E
authors.initials: E
authors.lastname: Landais
authors.forename: E
authors.initials: E
authors.lastname: Houssaint
authors.forename: S P
authors.initials: SP
authors.lastname: Lee
authors.forename: A B
authors.initials: AB
authors.lastname: Rickinson
authors.forename: G S
authors.initials: GS
authors.lastname: Taylor
mesh_terms: D000918:Antibody Specificity; D000956:Antigens, Viral / Q000276:immunology*; D015704:CD4 Antigens / Q000032:analysis / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018929:Cell Culture Techniques; D002472:Cell Transformation, Viral; D000939:Epitopes / Q000032:analysis / Q000276:immunology; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D015704:CD4 Antigens; D000939:Epitopes