Taylor GS, Long HM, Haigh TA, Larsen M, Brooks J, Rickinson AB. A Role for Intercellular Antigen Transfer in the Recognition of EBV-Transformed B Cell Lines by EBV Nuclear Antigen-Specific CD4+T Cells.
THE JOURNAL OF IMMUNOLOGY 2006;
177:3746-56. [PMID:
16951335 DOI:
10.4049/jimmunol.177.6.3746]
[Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The CD4+ T cell response to EBV may have an important role in controlling virus-driven B lymphoproliferation because CD4+ T cell clones to a subset of EBV nuclear Ag (EBNA) epitopes can directly recognize virus-transformed lymphoblastoid cell lines (LCLs) in vitro and inhibit their growth. In this study, we used a panel of EBNA1, 2, 3A, and 3C-specific CD4+ T cell clones to study the route whereby endogenously expressed EBNAs access the HLA class II-presentation pathway. Two sets of results spoke against a direct route of intracellular access. First, none of the clones recognized cognate Ag overexpressed in cells from vaccinia vectors but did recognize Ag fused to an endo/lysosomal targeting sequence. Second, focusing on clones with the strongest LCL recognition that were specific for EBNA2- and EBNA3C-derived epitopes LCL recognition was unaffected by inhibiting autophagy, a postulated route for intracellular Ag delivery into the HLA class II pathway in LCL cells. Subsequently, using these same epitope-specific clones, we found that Ag-negative cells with the appropriate HLA-restricting allele could be efficiently sensitized to CD4+ T cell recognition by cocultivation with Ag-positive donor lines or by exposure to donor line-conditioned culture medium. Sensitization was mediated by a high m.w. antigenic species and required active Ag processing by recipient cells. We infer that intercellular Ag transfer plays a major role in the presentation of EBNA-derived CD4 epitopes by latently infected target cells.
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