Dose-response effect of IFNγ on relative c-kit fluorescence. Day-5 cells were incubated with rhIFNγ (500 U/mL [A], 1,000 U/mL [B], 2,500 U/mL [C], and 5,000 U/mL [D]) for 24 hours at 37°C and then antibody was added and data were analyzed as described in the Materials and Methods. Expression of c-kit fluorescence is shown for untreated control cells (□) and control cells remaining (▪) after subtraction of data from IFNγ-treated cells. The figures in the upper right corners indicate the relative fluorescence of control cells over that of IFNγ-treated cells. ECFC purity in control cells was 76% ± 2% and in rhIFNγ-treated cells was 76% ± 3% (500 U/mL), 76% ± 3% (1,000 U/mL), 80% ± 1% (2,500 U/mL), and 72% ± 4% (5,000 U/mL), respectively.