Phagocytosis of DVs induces ROS production in PMNs. (A) PMNs were laden with dichlorol-fluorescein to visualize ROS generation at the single-cell level. Phagocytosis of DVs was accompanied by triggering of the respiratory burst, and ROS generation was seen to surround intracellular DVs. ROS generation was not observed when DVs were just attached to the cells (arrows). Scale bar indicates 10 μm. (B) Luminol-based chemiluminescence assay for ROS generation in PMNs during phagocytosis of DVs revealed a bell-shaped response curve covering a time span of 30-40 minutes. PMNs were challenged with 3-5 DVs/cell and the chemiluminescence response was recorded in the presence of 10% active or heat-inactivated human serum. One representative experiment of 3 independent experiments is shown.