EP/EL induces necrosis/apoptosis of THP-1 cells but do not impair innate immune functions of normal white blood cells.

<p>(A) Flow cytometric analysis of THP-1 cells and blood monocytes upon treatment with EP and EL. THP-1 cells and blood monocytes were treated with EP and EL at increasing concentrations (1 to 20 mM) for 12 h at 37°C, then stained with annexin-V-FITC/PI, and apoptosis/necrosis was determined by flow cytometry. Results of four independent experiments are shown. The columns depict the mean percentage of vital cells, apoptotic cells, and necrotic/late apoptotic cells. Apoptotic cells are annexin-V-positive only, whereas necrotic cells are PI-positive and annexin-V-positive. (B) Time-dependent effects of EP on death induction of THP-1 cells and blood monocytes. THP-1 cells (upper row) and PBMCs (lower row) were treated with 20 mM EP for 3, 12 and 24 h and apoptosis/necrosis is measured. Controls represent untreated cells (n = 3). (C) Effect of EP at phagocytic and burst activity of blood cells. Heparinized human whole blood was incubated with increasing concentrations of EP at 37°C and 6 h, and a sample without stimulus served as negative background control. Blood was further incubated with fluorescein-labeled opsonized <i>E</i>. <i>coli</i> bacteria for 10 min at 4°C or 37°C, respectively, to measure phagocytic activity. Burst activity was analyzed by treatment of blood with 2 x 10⁸ opsonized, non-labelled E. coli for 10 min at 4°C and 37°C in the presence of dihydrorhodamine 123. The mean fluorescence intensity (MFI) of monocytes and granulocytes were identified by flow cytometry (n = 3).