Figure 3. Lysosomal membrane permeabilization induced by heat stress in SW480 cells.

SW480 cells underwent intense heat stress (43°C) for 2h and were further incubated at 37°C for different times as indicated (0h, 1h, 3h, 6h, 12h or 24h). Cells were labeled with5 μM acridine orange (AO). A. Confocal laser scanning microscopy images of fluorescently labeled cells (×400). B. Flowcytometry analysis to count cells with a reduced number of intact lysosomes (‘pale cells’). C. The histogram represents the quantification of ‘pale cells’ analyzed by flow cytometry after heat stress. The data shown represent the mean ±SD of at least three independent experiments, performed in duplicate. *P < 0.05, statistically significant relative to control (37°C).