Wogonoside induces differentiation of U937, HL-60, and primary leukemic cells from AML patients. (A) Representative Wright-Giemsa staining for morphological examination is shown. Leukemic cells were treated with 1 μM ATRA, 100 μM wogonoside, or 150 μM wogonoside for 96 hours. Original magnification was ×400 (objective lenses ×40) under a light microscope (IX51; Olympus, Tokyo, Japan), and images were captured using DP2-BSW software (Olympus) at room temperature. (B) Detection of NBT-reduction activity of the leukemic cells is shown. NBT-positive cells with purple-black color were counted, and the overall percentage was calculated based on 200 total cells per microscopic field and counting 5 times in each group. (C) The effect of wogonoside on α-naphthyl acetate esterase activity is shown. (D) The expression of CD11b/CD14 in U937 and HL-60 cells is shown. The percentages of cells expressing CD11b and CD14 were detected by flow cytometry analyses. The data represent the mean ± SEM of 3 different experiments. Asterisks denote statistically significant (P < .05) differences compared with controls by one-way ANOVA.