Alveolar Epithelial Cell Line, A549 Cells Inhibit Neutrophil Apoptosis

Though cellular localization at the site of an inflammatory challenge is the critical first step in a neutrophil response, little has been known about the effects of alveolar epithelial cells on the dynamics of neutrophils. To investigate these effects, we used human purified neutrophils incubated with monolayers of human alveolar epithelial cells (A549), quiescent or preactivated with recombinant human tumor necrosis factor (TNF)-α for 24 h. Laser scanning cytometry (LSC) was employed to detect nuclear morphological changes and quantitate DNA strand breaks in neutrophils. The experiments revealed that A549 cells inhibited neutrophil apoptosis, and that this inhibitory effect was enhanced when the A549 cells were preactivated with TNF-α for 24 h. These results suggest that alveolar epithelial cells may be potentially able to contribute to promote inflammatory mechanisms by delaying neutrophil apoptosis.