An in vitro cell model system for the study of the effects of ozone and other gaseous agents on phagocytic cells.

Ozone (O(3)), a major component of air pollution and a very strong oxidizing agent, can lead to lung injury associated with edema, inflammation, and epithelial cell damage. The ozone effects on pulmonary immune cells have been studied by various in vivo and in vitro systems. In this report, we characterized a model system of cells of monocyte/macrophage lineage (THP-1 cells) exposed to ozone in vitro by studying cell viability and cell surface marker expression. THP-1 cells exposed to ozone in concentrations ranging from 0.1 to 0.5 ppm for 1 h were analyzed for cell viability and apoptosis (Annexin V/7-Amino-actinomycin D (7-AAD) flow cytometric assay) either immediately after ozone exposure or at later time points. This analysis showed absence of apoptosis and a small decrease in cell viability (5-17%) in ozone-exposed THP-1 cells. Cell surface protein expression (CD14 and CD11b) did not change following ozone exposure, but the effect of lipopolysaccharride (LPS) on TNF-alpha production following ozone exposure changed compared to filtered air/LPS-exposed cells. These findings indicate that this in vitro ozone cell-exposure system may be used in studies where the effects of various agents (physiological and non-physiological) on phagocytic cells can be analyzed. This model system offers conditions where the experimental results are not due to cell death, but rather due to the effects of ozone and/or agents under investigation.