Cytolytic activity of T-cell lines generated from 10 donor/recipient pairs against recipient- and donor-derived EBV-LCL targets. Lines were tested 4 to 6 weeks after initial stimulation for lytic activity against recipient-derived (□) or donor-derived (▪) EBV-LCL targets in a standard 4-hour ⁵¹Cr release assay at an effector to target (E:T) ratio of 20:1.