Uptake of HPTS-SL and acridine orange

by human Mφ (Α, Β), mature DC (C, D), and immature DC (E, F). Cells were incubated with HPTS-SL for 24 hours, and acridine orange was added for the last 30 minutes of culture. Cells were washed and mounted on a glass slide, and photographs were taken under a fluorescence microscope at an excitation of 350 nm to 410 nm (left) and 450 nm to 490 nm (right), respectively (magnification, 400×). Arrowheads highlight HPTS-SL in each panel; note that in Mφ most of the HPTS-SL are colocalized with acridine orange and not visible at 450 nm to 490 nm, whereas SL in DC are separated from acridine orange and visible at both wavelengths.