Fig. 4.
Inflammatory response to particles collected at industrial sites. Cytokine responses were measured in cell culture supernatants of J774A.1 cells exposed to size-fractionated particles (n = 3 independent experiments). a Interleukin (IL)-6 levels released by J774A.1 cells in response to a 24 h exposure to UFP, PM0.1–2.5, PM2.5–10 and PM>10 from industrial sites. Three-way ANOVA, Dose x Site x Size interaction, p = 0.002. For simplicity, only significant dose effects relative to 0 μg/cm2 within a Site and Size are presented (*p < 0.05, Holm-Sidak). b Hierarchical clustering of particles according to cytokine response in J774A.1 cells. The heat map displays particle potency estimates determined for each cytokine from the slope of the dose-effect relationship. General descriptions of the clusters are presented on the right. Red, increased expression; green, decreased expression. HB, Hamilton Beach steel mill; MA, Montréal petrochemical refinery; MC, Montréal copper smelter; SR, Sarnia petrochemical refinery; SW, Shawinigan aluminum smelter