Human airway tracheobronchial epithelial cells isolated from airway specimens from patients without underlying lung disease were provided by the National Disease Research Interchange (NDRI, Philadelphia, PA) or as excess tissue following lung transplantation under University of North Carolina at Chapel Hill (UNC) Institutional Review Board-approved protocols by the UNC Cystic Fibrosis Center Tissue Culture Core. Primary cells derived from single patient sources were expanded on plastic to generate passage 1 cells and plated at a density of 3610 5 cells per well on permeable Transwell-Col (12-mm diameter) supports (Corning, Inc.). HAE cultures were grown in custom media with provision of an air-liquid interface for 4 to 6 weeks to form differentiated, polarized cultures that resemble in vivo pseudostratified mucociliary epithelium, as previously described [50] . Madin-Darby Canine Kidney (MDCK) cells were maintained in DMEM (Gibco-Invitrogen, Inc.) supplemented with 10% fetal bovine serum and 1% penicillin / streptomycin (Sigma-Aldrich, Inc.).