Construction and functionality of the retroviral vectors. Panel A is the schema of the retroviral vectors used to transduce EBV-CTLs. Panel B is a Western blot analysis showing the expression of ΔCD34 (top panel) and caspase-9 (middle panel) in COS-7 cells transduced with either iC.ΔCD34/IL-2v or iC.ΔCD34/IL-15v or ΔCD34v vectors. The lower gel shows the membrane reprobed with anti-GAPDH antibody. Panel C shows the transduction efficiency of EBV-CTLs measured as expression of a truncated form of CD34 (ΔCD34) on the cell surface by FACS analysis. Plots from a representative experiment are shown. Panel D illustrates the kinetics of cytokine release by EBV-CTLs transduced with either iC.ΔCD34/IL-2v or iC.ΔCD34/IL-15v or ΔCD34v vectors and stimulated with EBV-LCLs. Cytokines were detected in the culture supernatant at the indicated time after EBV-LCL stimulation and measured by specific ELISAs.