Exogenous hepcidin does not alter iron transport in NHBE cells or alveolar macrophages. Differentiated NHBE cells (A) or alveolar macrophages (B) were loaded with 57Fe for 4 hours, followed by treatment with exogenous hepcidin peptide (1 μM) for an additional 20 hours. Cells were washed and scraped into 3 N HCl/10% trichloroacetic acid. After hydrolysis at 70°C for 24 hours, 57Fe was quantified. The quantity of exogenous 57Fe was compared to the naturally occurring 56Fe and showed no change in either the airway epithelial cells or alveolar macrophages treated with exogenous hepcidin peptide.