B lymphoblastoid cell lines as efficient APC to elicit CD8(+) T cell responses against a cytomegalovirus antigen

Potent and readily accessible APC are critical for development of immunothe rapy protocols to treat viral disease and cancer, We have shown that B lymp hoblastoid cell lines (BLCL) that stably express CMV phosphoprotein 65 (BLC Lpp65), as a result of retroviral transduction, can be used to generate ex vivo CTL cultures that possess cytotoxicity against CMP and EBV. In this re port, we demonstrate that the EBV-specific cytotoxicity in the BLCLpp65-pri med culture had a spectrum of EBV-Ag recognition similar to that of the BLC L-primed counterpart, suggesting that retroviral transduction and expressio n of the CMV Ag would not compromise the Ag-presenting capacity of BLCL. In addition, BLCLpp65 appeared to present multiple natural pp65 epitopes, bec ause pp65-specific CTL, which recognized different CMV clinical isolates, w ere generated in BLCLpp65-primed cultures from individuals with various HLA backgrounds. Consistent with a polyclonal expansion of virus-specific CTL, T cell lines established from the BLCLpp65-primed CTL cultures expressed d ifferent TCR-V-beta. Although most of the virus-specific T cell isolates we re CD8(+), EBV-specific CD4(+) lines were also established from BLCLpp65-pr imed cultures. Western blot analysis revealed that the CD8(+) lines, but no t the CD4(+) line, expressed granzyme B, consistent with features of classi c CTL. Thus, our results suggested that BLCL stably expressing a foreign Ag might be used as a practical APC to elicit CD8(+) T cell responses.