Effect of growth factor stimulation on lentivector- or oncoretrovirus vector–mediated ex vivo functional correction of oxidase activity in X-CGD CD34⁺PBSCs.

Shown is oxidase activity at 17 days of culture following a single 7-hour transduction of nondividing or proliferating X-CGD CD34⁺PBSCs using either third-generation SIN lentivector–gp91^phox or MFGS–gp91^phox (average of 2 experiments). For the first 2 days of culture, including transduction on day 1, PBSCs were maintained in FLT3-L (50 ng/mL) alone (proliferation nonpermissive conditions, ■) or in the 5-cytokine combination (proliferation-permissive conditions, ▨). Twenty-four hours after transduction, all cells were switched to fresh medium containing the 5-cytokine combination. PMA-stimulated superoxide generation (chemiluminescence assay) is expressed as percentage of the stimulated oxidase activity of a similar 17-day culture of normal CD34⁺PBSCs. Negative control: nontransduced X-CGD CD34⁺PBSCs at 17 days of culture demonstrated PMA-stimulated superoxide generation that was 0.3% of the normal control (not shown).