IL-2 and IL-15 transgenic CTLs expand in response to antigen stimulation. EBV-CTLs transduced with either iC.ΔCD34/IL-2v or iC.ΔCD34/IL-15v or ΔCD34v vectors were maintained in culture and stimulated once a week with autologous LCLs (E/T ratio 1:1) without addition of exogenous cytokines. Control EBV-CTLs transduced with the ΔCD34v vector were maintained in culture by adding rhIL-2 (50 U/mL). Data represent the mean plus or minus SD of cell expansion of 5 donors (panel A). IL-2 or IL-15 transgenic EBV-CTLs did not significantly expand when they were maintained in culture without specific antigen stimulation. Data represent the mean plus or minus SD of cell expansion of 3 donors (panel B).