Study of EBNA1-specific cellular immune responses in EB-virus associated diseases in chilhood

点击翻译按钮获取中文摘要

Epstein-Barr virus (EBV) -encoded nuclear antigen I (EBNA1) is an attractive target for immunotherapy against EBV-associated malignancies because it is expressed in all EBV-positive cells. Although CD^8+ cytotoxic T-lymphocyte (CTL) epitope presentation is largely prevented by its unique domain, the use of mRNA-transduced dendritic cells (DCs) would offer the advantage of priming EBNAl-specific CTLs. After stimulation with EBNA1 transduced monocyte-derived DCs, we successfully isolated two EBNA1-specific OTL clones B5 and C6 from a healthy donor. These Oils recognize peptides in the context of HLA-B*3501 and HLA-Cw*0303, respectively. We then identified a novel epitope FVYGGSKTSL presented by both HLA-Cw*0303 and Cw*0304, which are expressed by 40 % of Japanese. We made fluorescently labelled MHC-tetramers to detect EBNA1-specific CTLs by flow cytometry. The mixed lymphocyte-peptide culture method, which enabled us to estimate frequencies of EBNA1-specific CTLs, revealed that FVYGGSKTSL-specific CTL precursor frequencies in HLA-Cw*0303 or Cw*0304-positive donors were between 1 x 10^-5 and 1 x 10^-4 CD^8+ T cells. Moreover, both CTL clones inhibited growth of HLA-matched BEV-transformed B lymphocytes in vitro and B5 CTLs produced an IFN-y response to EBNA1-expressing gastric carcinoma cells in the context of HLA-Cw*0303.Accumulating current evidence indicates that CD^4+ T cells,as well as CTLs, are required for effective antitumor immunity. We investigated the ability of CD^4+. T cell clones induced with overlapping peptides covering EBNA1, and identified minimal epitopes and their restricted MEIC class II molecules. Of these, one clone recognized a novel epitope being presented by DRB1*0401, 0403, and 0406.