Characterization of three-week old BMMC cultures. Histamine staining: slides treated with rabbit IgG (Panel a, d) vs rabbit anti-histamine (Panel b, e). Toluidine blue staining: 5 × 104 BMMC were prepared onto a cytospin slide, examined respectively with 20× (Panel c) and 100× objectives (Panel f). Surface FcεRI and c-kit expression: BMMC were stained with PE-anti-c-kit and FITC-anti-FcεRI analyzed by flow cytometry. Numerically, 98.7% c-kit + cells are mast cells, including c-kit +, FcεRIhi cells (quadrant 3, 90.84%), and c-kit +, FcεRIlo cells (quadrant 2, 7.85%) (g). The procedures were described in Materials and methods.