RT Journal Article SR Electronic T1 Resistance of quiescent and proliferating airway epithelial cells to H2O2 challenge JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 633 OP 642 DO 10.1183/09031936.00093906 VO 29 IS 4 A1 M. P. Smit-de Vries A1 M. van der Toorn A1 R. Bischoff A1 H. F. Kauffman YR 2007 UL http://erj.ersjournals.com/content/29/4/633.abstract AB Alveolar epithelial cell injury and recovery are important in the pathogenesis of oxidant-induced lung damage. The alveolar cell line A549 was used to study responses of proliferating and quiescent cells in culture to time- and dose-dependent hydrogen peroxide (H2O2) challenges. Recovery was monitored after 24 h of incubation in fresh medium with 10% serum. The adherent cells were counted and the resistance and recovery of the attached cells was assessed by appearance, by measuring the number of viable, apoptotic and necrotic cells using fluorescent-activated cell sorting, and by determining the intracellular free thiol content. A549 cells recovered from a 1-h challenge with up to 1 mM H2O2 but could not sustain a more prolonged challenge (6 or 24 h) with 0.5 mM or 1.0 mM H2O2. These more severe conditions resulted in: loss of cells by detachment from the plate surface; reduced numbers of viable cells primarily due to necrosis; and a strong reduction of the intracellular free thiol content. Quiescent cells proved to be more sensitive to oxidative stress than proliferating cells. Intracellular free thiol levels apparently play a decisive role in cell survival, preferentially protecting proliferating cells.