Effect of T_H1 and T_H2 cytokines on CD34⁺ growth and differentiation.Peripheral blood CD34⁺ cells were grown in medium supplemented with SCF (100 ng/mL) in combination with IFN-γ (10 ng/mL), IL-4 (10 ng/mL), or IL-5 (10 ng/mL) for 8 weeks. Total cell (A) and mast cell (B) numbers were monitored throughout the culture. Data represent mean ± SEM from 5 donors. (C) 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. Data are representative of 5 donors. (D-E) Receptor expression of CD34⁺ cells during cell division in the first week of culture. 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. Cells were labeled with anti–Kit-PE, anti-CD34⁺, and propidium iodide (PI), and the mean fluorescence intensity (MFI) of Kit (D) and CD34⁺(E) expression of PI-negative cells in each generation was analyzed by flow cytometry. Data are representative of 5 donors. Data in graphs are presented as mean ± SEM (n = 5).