Figure 3.

IL-6 release and PGE₂ synthesis in alveolar macrophages by 1.5 and 0.5 μm Fe₂O₃ particles (in vitro study). Rat alveolar macrophages were incubated with large 1.5 μm or small 0.5 μm Fe₂O₃ particles for 24 h in RPMI, respectively, and studied in absence and presence of PGE₂ synthesis inhibitor indomethacin: (A) release of IL-6 as pro-inflammatory mediator, and (B) synthesis of PGE₂ as anti-inflammatory and immune-modulating mediator. Data are given as mean ± SD of the percentages for IL-6 release and PGE₂ synthesis obtained from cells of 4 different animals (n = 4). Baseline value represents 100% of IL-6 release with 304 ± 105 pg/mL (n = 4), and 100% for PGE₂ synthesis with 408 ± 140 pg/mL (n = 4). P-values (* P < 0.05; ** P < 0.005) for significant difference between baseline and particle-treated cells in the absence and presence of indomethacin and (# P < 0.01) for significant difference between large 1.5 μm and small 0.5 μm Fe₂O₃ particles in absence of indomethacin for IL-6 release (A) and PGE₂ synthesis (B).