Figure 4.

Macrophage phagocytosis of LL-37-induced secondarily necrotic PMN. PMN were incubated previously for 20 h, with or without LL-37 (or scrambled LL-37) at the stated concentrations, and then incubated with hMDM for 1 h before removal of noningested PMN. Phagocytosis was assessed by (A) light microscopy, counting the proportion of MDM peroxidase-positive cells; n = 3 donors for each condition and n = 2 replicates/experiment; or (B) flow cytometric analyses, evaluating the proportion of MDM ingesting Cell Tracker Green-stained PMN; n ≥ 3 donors for each condition, with n = 2 replicates/experiment. As a positive control, wells of adherent monocytes were also cultured in the presence of 1 μM dexamethasone for 5 days to up-regulate MDM phagocytosis of dead PMN. Significance was assessed by one-way ANOVA with Bonferroni’s multiple comparison test comparing each treatment with control; *, P ≤ 0.05; **, P ≤ 0.01.