Fig. 4.

Release of neutrophile elastase, but not of oxygen radicals is increased in neutrophil-A549 co-cultures. Monocultures of neutrophils (7.5 × 10⁶/ml) or co-cultures of neutrophils (7.5 × 10⁶/ml) and A549 cells (PMN + A549) were activated with fMLP (1 µM). Experiments were performed in the presence of LPS [0.1 µg/ml]. a Elastase release: 10 min after fMLP stimulation, cell supernatants were collected and centrifugation was performed at 4 °C at 1,200×g. The cell-free supernatant was harvested and analyzed for elastase activity in an Uvicon Spectrophotometer. Horizontal bars indicate averages of twenty independent experiments. b Respiratory burst: duplicate reaction mixtures containing 75 µM ferricytochrome in the presence or absence of 10 µg/ml superoxide dismutase were performed. 10 min after fMLP stimulation, incubations were terminated by centrifugation at 4 °C at 1,200×g. O₂ ⁻ release was quantified as relative extinction at 550 nm in an Uvicon Spectrophotometer. Horizontal bars indicate averages of eight independent experiments