Resting lymphocytes stimulated with IL-2, IL-7, or IL-15 in the absence of TCR triggering are efficiently transduced by lentiviral vectors. Resting T lymphocytes were isolated and purified from healthy donors as described in “Materials and methods.” Cells were cultured in the presence of 10 U/mL IL-2, 5 ng/mL IL-7, or 10 ng/mL IL-15. After 96 hours of stimulation resting T lymphocytes were transduced by LV. (A) Expression of ΔLNGFr 96 hours after transduction. The percentage of positive cells is shown. Only viable cells, as assessed by propidium iodide (PI) exclusion, were analyzed. (B) Cells were labeled with CFSE before stimulation with cytokines and analyzed at the day of transduction for CFSE intensity by flow cytometry. (C) DNA and RNA contents at the day of transduction were measured by 7AAD and PY staining, respectively. The percentage of cells in S/G₂/M phases is indicated. The R2 gate, encompassing the G₀/G₁ population was used for further analysis. (D) Histogram of RNA staining of R2-gated cells plotted for PY staining to distinguish G₀ from G₁ cells. The percentage of cells in G₁ is indicated. Data are representative of 4 experiments.