CD4+ T-Cell Responses to Epstein-Barr Virus (EBV) Latent-Cycle Antigens and the Recognition of EBV-Transformed Lymphoblastoid Cell Lines

CRUK Institute for Cancer Studies, The University of Birmingham, Vincent Dr., Edgbaston, Birmingham B15 2TT, United Kingdom.
Journal of Virology (Impact Factor: 4.44). 05/2005; 79(8):4896-907. DOI: 10.1128/JVI.79.8.4896-4907.2005
Source: PubMed


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.

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Available from: Elise Landais, Jan 08, 2014
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    • "One of the most extensively studied ThCTL subsets in humans are those generated against Epstein Barr Virus (EBV), a herpes virus typically harbored in latent form by B cells. ThCTL have been found to recognize both lytic and latent EBV class II antigens presented by conventional and transformed B cells [16–19]. ThCTL have also been identified in HIV-1 seropositive individuals [7, 12], a lentivirus that infects professional APCs and CD4 T cells that can also express class II upon activation in humans but not in mice [20–22]. "
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    • "Outgrowth assay was carried out as previously described [12]. Briefly, target LCL were seeded as replicates in U-bottom 96-well plates at doubling dilution, starting from 104 cells/well to 78 cells/well. "
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    • "The results in Fig. 2 suggest that this recognition is impaired by the V-protein through its multiple effects on the MHC class I antigen presentation pathway and on the expression of adhesion molecules necessary for efficient CTL–target binding. To test this hypothesis, we compared the recognition of IARC-171 pBabe and V-protein LCLs by EBV-specific CD8 + CTLs using an ELISA for IFN-c released by T cells that gives a quantitative measurement of the T cell recognition of the EBV + target cells (Long et al., 2005). This assay was only performed on IARC-171 pBabe and V-protein LCLs as they demonstrated the biggest difference in MHC class I cell surface expression (Fig. 2) and the HLA-type was matched to two available T cell clones: HPV (Blake et al., 1997) and AVF (Gavioli et al., 1993). "
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