IL1A and bronchiolitis obliterans syndrome: This study demonstrates that a Pseudomonas aeruginosa challenge of lung epithelial cells causes the release of IL‐1α and the induction of an inflammatory phenotype in lung fibroblasts, and provides evidence of an association between infection with P. aeruginosa, IL‐1α levels in bronchoalveolar lavage fluid, and the development of bronchiolitis obliterans syndrome following lung transplantation.