Virus-specific activity of CTL as determined by Cr release assay. ⁵¹Cr release at 4 hours after coincubation of CTL lines with autologous nontransduced EBV-LCL (EBV target), autologous EBV-LCL transduced with Ad5f35^null vector, or recipient PHA blasts (allogeneic target). Lines made from haploidentical donors are shown in the top panel (n = 8) and those made from matched unrelated donors are shown in the bottom panel (n = 12). The data are mean percentage lysis (± SEM) of targets by all 20 CTL lines at E/T ratios of 40:1, 20:1, 10:1, and 5:1.