DC generated from transduced CD34⁺ CB cells. Bivariate dot plots of flow cytometric measurement of Nef⁻ transduced cells (top) and Nef⁺ transduced cells (bottom). (A) CD4-APCy versus EGFP expression of cells at day 5, day 9, and day 14 of culture, as indicated. (B) CD4-APCy versus CD80-PE expression of cells shown in (A), gated on EGFP⁺ cells at day 9 and day 14 of culture, as indicated. Quadrants were set to include 99% of cells stained with isotypic controls and EGFP⁻ cells in lower left quadrant. Figures indicate percentage of cells present in corresponding quadrants. (C) Proliferation of PBMCs seeded on irradiated sorted mature Nef⁻ (⧫) or Nef⁺ (□) transduced DCs, measured by ³H-thymidine incorporation. Ratio S/R, ratio between number of DCs (stimulators, S) over number of PBMCs (responders, R); cpm, counts per minute. Points represent average of triplicate wells and error bars indicate standard deviation.