The requirement for IRF8 in GATA1 and GATA2 expression, and the effect of GATA1 and GATA2 transduction on basophil and mast cell development in Irf8^−/− progenitor cells. (A) Gata1 and Gata2 mRNA expression in WT and Irf8^−/− GPs was measured by RT-qPCR. GPs from each genotype were sorted into 3 separate tubes and analyzed by RT-qPCR. Values in the bar graph are means ± standard deviations. (B) GATA2 protein expression in WT and Irf8^−/− GPs was examined by immunostaining followed by flow cytometry. ΔMFI (mean fluorescent intensity) was calculated by subtracting the background fluorescence intensity. Values in the bar graphs are means ± standard deviations from 3 independent experiments. (C) Gata1 and Gata2 mRNA expression in WT and Irf8^−/− Lin⁻ cells transduced with empty MICD8 vector (Ctrl) or MICD8-IRF8 as in Figure 5A. Transduced cells were purified by the magnetic-activated cell sorting (MACS) system on day 5 and analyzed by RT-qPCR. Values in the bar graphs are means ± standard deviations from triplicate samples. (D) Bone marrow Lin⁻ cells from WT and Irf8^−/− mice were transduced with empty MIG vector (Ctrl), MIG-GATA1, or MIG-GATA2 as in Figure 5A. Retrovirally transduced (GFP⁺) cells were analyzed for basophil and mast cell generation on day 5. Values in the bar graphs are means ± standard deviations from triplicate samples. Data are representative of 2 independent experiments with similar results. *P < .05; **P < .01; ***P < .001 (Student t test). NS, not significant.