Dot plot of the DHR FACS oxidase analysis of 17-day cultures of differentiating CD34⁺ cells. Each dot represents a single “event” (cell) analyzed for side scatter (granularity) plotted in linear scale on the vertical axis, and for fluorescence (oxidant production) plotted in log scale on the horizontal axis. The analysis was gated to include all live cells in the cultures following loading with DHR and activation with PMA. The top panel shows analysis of a typical sham treated normal CD34⁺ 17-day culture. In this normal CD34⁺ cell culture, two clusters of cells can be seen that are separated by the vertical line. The large cluster on the left represents immature cells with low-oxidase activity, whereas the smaller cluster to the right represents mature granulocytes (as determined by sorting) with high oxidase activity. The middle and lower panels show analyses of sham treated and MFGS-p67^phox transduced p67^phox deficient CGD CD34⁺ cultures, respectively. Mature granulocytes with high oxidase activity are only seen in patient cultures after transduction as in the lower panel.