Fig. 4
Excretory/secretory products enhanced the phagocytosis activity of neutrophils. a, b ESP enhanced the phagocytosis of live EGFP-Escherichia coli by neutrophils. Neutrophils were infected with EGFP-E. coli (MOI 25) (green fluorescence) for 2 h. Higher magnifications of selected phagocytosis areas are shown on the rightmost side. The arrowheads indicate the EGFP-E. coli ingested by neutrophils. The bars in the original image represent 40 μM (excluding the rightmost magnifying box). c–e Representative images of neutrophils untreated (c) or pre-treated with 10 ng/μl ESP (added ATA) (d) for 2 h, showing increased phagocytic activity after ESP pretreatment. e A total of 5 × 105 neutrophils per ml was incubated with 1 × 107 EGFP-E. coli per ml for 2 h. After co-incubation, the viable bacterial counts in the supernatant were calculated. Values are means (± standard error mean, SEM) (shown by error bars) of at least three independent experiments. **P < 0.01. f Neutrophils, either pre-treated or untreated, were incubated with bioparticles from Vybrant Phagocytosis Assay Kit for 2 h in the dark. The phagocytic index of neutrophils untreated or pre-treated with different concentrations of ESP (added ATA) (1, 2, 5, and 10 ng/μl) for 2 h at 37 °C (means ± standard error mean; N = 5; *P < 0.05). ESP, excretory/secretory products; ATA, aurintricarboxylic acid; EGFP, E. coli, enhanced green fluorescent protein-E. coli