Figure 4

Cell death in cultures of murine J774 macrophages that were treated with azithromycin (AZM) for 45 min or high-molecular-weight desferrioxamine (H-DFO)/ammonium chloride (NH ₄ Cl) for 4 h at the indicated concentrations and then oxidatively stressed. Cell death, which appeared 10 h after the end of the oxidant challenge, was assessed by typical morphology using a phase contrast microscope and by the fraction of apoptotic DNA (both methods gave similar results for apoptosis). In some experiments, the cells were pretreated with 10 mM NH₄Cl for 5 min (to raise the lysosomal pH, which largely prevented the uptake of the lysosomotropic compound AZM) and then exposed to AZM in the continued presence of NH₄Cl (for details see the Methods section). In the non-oxidatively stressed cultures, cell death was < 3%. Values are the means ± 1 SD (n = 4; independently performed). Significant differences are indicated as follows: ** p < 0.01 and *** p < 0.001 (vs. controls) and ^§ p < 0.05 (AZM + NH₄Cl treated cells vs. AZM treated cells).