Expression and regulation of hepcidin mRNA in primary monocytes and THP-1 cells by LPS, IL-6, and iron. THP-1 cells (C-E) were stimulated for 3, 6, 12, and 24 hours with 1μg/mL LPS (C), 10 ng/mL IL-6 for (D), or 50μM ferric chloride (E). Freshly isolated human monocytes were stimulated for 6 hours with 1 μg/mL LPS (A) or 10 ng/mL IL-6 (B). After that, cells were subjected to RNA preparation, followed by reverse transcription and quantitative TaqMan PCR. Specific values of target genes were normalized to those of beta-actin. Data are depicted as lower quartile, median and upper quartile (boxes), and minimum/maximum ranges (whiskers; *P < .05, control cells vs stimulated cells by Student t test).