An in vitro system for exposure of lung cells to gases: Effects of ozone on rat macrophages

Abstract

A test system was developed for the in vitro exposure of lung cells to gases. The exposure system was used to evaluate ozone (O3) injury to pulmonary alveolar macrophages (PAM) obtained from Sprague-Dawley rats by bronchopulmonary lavage. Ozone exposures were conducted within temperature-controlled stainless-steel and Plexiglas chambers that contained glass petri dishes affixed to a revolving, inclined platform. Cell exposures were accomplished by rotation of the platform at 1 rpm to alternately expose PAM monolayers to culture media and O3. The system provided stable, O3-containing atmospheres and permitted simultaneous in vitro exposures at three O3 concentrations. In vitro exposure of PAM monolayers for 2 h at chamber concentrations ranging from 0.2 to 6.1 ppm O3 was associated with a significant, concentration-related reduction of latex-bead phagocytosis in rotated PAM cultures. In contrast, PAM that were similarly exposed in nonrotated dishes placed horizontally and covered with a stationary layer of media (1.5 mm depth) were not affected. Other parameters of cell function, including PAM viability and adherence, were unchanged compared to unexposed or horizontal, nonrotated controls. The inability to observe adverse effects among the nonrotated cultures is consistent with the impaired diffusion of O3 through the comparatively thick media overlay in stationary cultures. The in vitro system provides a realistic simulation of lung cell exposure to O3 and represents a useful model to study the toxicity of gases on cultured cells.