A Biological Assessment of the Oxidative Potential of a Selection of Ambient Pm2.5 Samples from Fresno and Claremont, California

Evidence suggests that Particulate Matter, PM2.5, exposure in humans leads to respiratory inflammation through an excess of reactive oxygen species (ROS) production initiated by alveolar macrophages. It is unclear which particle components are responsible for the biological response, but certain organic hydrocarbons, such as quinones, and transition metals like copper are of interest due to their ROS-generating, redox-cycling reactions. In the current study, we investigate the effects of ambient PM2.5 samples collected from Fresno and Claremont, California on ROS metabolism in the rat alveolar macrophage cell line NR8383. A microplate-based assay using the oxidant-sensing probe 2’,7’- dichlorofluorescein diacetate (DCFH-DA) was optimized in our laboratory to assess global ROS production in NR8383 exposed to the ambient PM2.5 samples. The goal is to obtain population-level ROS measurements from treated macrophages using a fluorescence microplate reader and flow cytometer. A representative Claremont sample and a Fresno sample were mass-normalized. The cell responses are significantly different from each other, 5.90 ±1.43FU/ μg PM2.5 and 0.86±0.31 FU/ μg PM2., respectively (p=0.05). When the samples were copper-normalized, a significant difference was obtain in cell response. The Fresno sample, 29.87±7.29 FU/μM of Cu sample and Claremont sample, 4.34±1.60 FU/μM of Cu sample (p=0.05).