CTL cultures at 21 days after ex vivo stimulation with autologous BLCLpp65 were tested for specific cytotoxicity against EBV-transformed BLCL, CMV-infected SF, and MSCVpp65-transduced cells in chromium release assay. (A through D) CTL activity from 4 CMV seropositive/EBV seropositive individuals. (E through F) CTL activity from 2 CMV seronegative/EBV seropositive individuals. (E:T ratio, 12.5:1).