Effect of T_H1 and T_H2 cytokines on mature human mast cells. Mature mast cells were generated by culturing CD34⁺ cells for 8 weeks in 100 ng/mL SCF. (A) Mature mast cells were stained with CFSE and cultured in medium containing SCF (100 ng/mL) and IFN-γ, IL-4, or IL-5 (all at 10 ng/mL) for 7 days. Division was assessed by flow cytometry. (B) Cells grown in medium containing SCF and IFN-γ, IL-4, or IL-5 for 7 days were sensitized with IgE overnight, then stimulated with antigen and analyzed for β-hexosaminidase release. Data in graphs are presented as the mean ± SEM (n = 5).