Induction of Epstein-Barr virus-specific cytotoxic T-lymphocyte responses using dendritic cells pulsed with EBNA-3A peptides or UV-inactivated, recombinant EBNA-3A vaccinia virus

Cell-mediated immunity, especially the cytotoxic T lymphocyte (CTL), provid es resistance to Epstein-Barr virus (EBV), as is demonstrated by the occurr ence of posttransplant lymphoproliferative disease in immunosuppressed pati ents. We set out to use dendritic cells (DCs) to elicit anti-EBV-specific C TLs in culture. In unselected, HLA-B8(+) donors, monocyte-derived mature DC s were pulsed with the HLA-B8- restricted EBNA-3A peptide, FLRGRAYGL, and a dded to autologous T cells for 7 days at a DC:T ratio of 1:5 to 1:60, The c ultured cells specifically lysed EBNA-3A peptide-pulsed, HLA-B8(+), B-lymph oblastoid cell lines in a 5-hour Cr-51-release assay. The generation of CTL s did not require the addition of interleukin-2. In comparison, monocytes w ere weak antigen-presenting cells. DCs were then infected with recombinant vaccinia-EBMA-3A, Vaccinia infection significantly decreased the viability of immature DCs after 3 days of culture (to 25% to 45%) but had a smaller e ffect on mature DC recovery (40% to 70%). To decrease these cytopathic effe cts and to expand the potential use of vaccinia vectors for DC therapy in i mmunocompromised patients, we successfully used psoralen and UV-inactivated virus. Mature DCs pulsed with either live or inactivated vaccinia EBNA-3A virus could elicit strong EBNA-3A-specific CTLs, Therefore, mature DCs are powerful stimulators of EBV-specific CTLs and their major histocompatibilit y complex class I products can even be charged with UV-inactivated recombin ant vaccinia. (C) 1999 by The American Society of Hematology.