Comparison of functionality of iFas and iCasp9_M in T cells. (A) EBV-CTLs were transduced with ΔNGFR-iFas.I.GFP (left) or iCasp9_M.I.GFP (right) and sorted for high GFP expression. Transduced CTLs were then mixed 1:1 with nontransduced CTLs. The percentages of ΔNGFR⁺/GFP⁺ and GFP⁺ T cells are indicated. (B) On the day of LCL stimulation, 10 nM CID was administered, and GFP was measured at the time points indicated to determine the response to CID. ♦ indicates ΔNGFR-iFas.I.GFP; ▪, iCasp9_M.I.GFP. Mean and standard deviation of 3 experiments are shown. (C) The human T-cell lines Jurkat (left) and MT-2 (right) were transduced with ΔNGFR-iFas.I.GFP (top row) or iCasp9_M.I.GFP (bottom row). An equal percentage of T cells was transduced with each of the suicide genes: 92% for ΔNGFR-iFas.I.GFP versus 84% for iCasp9_M.I.GFP in Jurkat, and 76% for ΔNGFR-iFas.I.GFP versus 70% for iCasp9_M.I.GFP in MT-2 (data not shown). T cells were either nontreated or incubated with 10 nM CID. Eight hours after exposure to CID, apoptosis was measured by staining for annexin V and 7-AAD. Representative example of 3 experiments is shown. PE indicates phycoerythrin.