RPMI 1640 medium was purchased from Biochrom (Berlin, Germany). FCS was from Life Technologies (Carlsbad, CA, USA). Penicillin and streptomycin were from PAA Laboratories (Pasching, Austria). PBS was obtained from PAN-Biotech (Aidenbach, Germany). EBSS was from Sigma-Aldrich (Saint Louis, MO, USA). Bronchial epithelial basal medium (BEBM) and supplementary growth factors were all from Lonza (Walkersville, MD, USA). PureCol (type I bovine collagen solution, 3 mg/ml) was from Advanced BioMatrix (San Diego, CA, USA). Soybean trypsin inhibitor (STI), DNase I, and Protease XIV were from Sigma-Aldrich. Primary antibodies detecting p-STAT1 and actin were all from Cell Signaling Biotechnology (Frankfurt, Germany). IFNλ antibody was from abcam (ab38569, Cambridge, UK).