Analysis of cell division and apoptosis through weeks 2 to 8. (A) Cell division in the second week of culture. One-week-old CD34⁺ cells were stained with CFSE (5 μM) and were cultured in medium containing SCF (100 ng/mL) and IFN-γ (10 ng/mL), IL-4 (10 ng/mL), or IL-5 (10 ng/mL) for 7 days. Division was analyzed by flow cytometry (n = 5). Because dividing cells become increasingly autofluorescent as they mature, the coefficient of variation within each fluorescence peak increases; statistical software was used to account for such variations and to mathematically calculate each division (represented by white lines). (B) Apoptosis of cells during entire 8-week culture. CD34⁺ cells were cultured in the presence of SCF and IFN-γ (10 ng/mL), IL-4 (10 ng/mL), or IL-5 (10 ng/mL) for 8 weeks. Apoptosis was analyzed by propidium iodide and annexin V–FITC labeling and was analyzed on a FACScalibur. Data in graphs are presented as the mean ± SEM (n = 5).