Effects of poultry DE on inflammatory gene expression in A549, Beas2B, small airway epithelial (SAE), and THP-1 cells. A549 (A), Beas2B (B) and SAE (D) cells were treated with medium alone or medium containing 0.25% DE for 3 h. THP-1 cells (C) were treated with medium alone or medium containing 0.1% dust extract for 1 h. Levels of mRNAs and 18 S rRNA were determined by quantitative RT-PCR, and mRNA levels normalized to 18S rRNA level. The level in cells treated with control medium (C) was arbitrarily set as 1, and levels in dust extract treated cells are shown relative to control level. Data shown are means ± SE/SD (n = 4–7 for A549 cells, n = 4–5 for Beas2B cells, n = 3 for THP-1 cells, and n = 2 for SAEC). *P < 0.05, **P < 0.01, ***P < 0.001, #P < 0.0001 compared with cells treated with control medium.