Study subjects: immunohistochemistry.

Lung parenchyma containing predominantly alveolar tissue from four IPF patients and from the Interstitial Lung Disease Clinic, University of California, Davis Medical Center (UCDMC), in Sacramento, CA were processed from surgical biopsies. Tissues were from deidentified deceased patients who were part of an IPF registry in our Interstitial Lung Disease Clinic. IPF diagnosis was confirmed based on medical history, physical examination, high-resolution computed tomography, pulmonary function tests, and diagnostic lung biopsy. In all cases, the pathological diagnosis was usual interstitial pneumonia confirmed by a licensed lung pathologist at UCDMC. For non-IPF lung tissue, lung parenchyma was obtained from macroscopically healthy segments of peripheral lung from four patients undergoing pneumonectomy or lobectomy surgery for lung cancer at the Section of Thoracic Surgery, Department of Medicine, University of Manitoba. Subjects were ex-smokers for at least 10 yr at the time of surgery, and based on preoperative lung function testing, exhibited no sign of obstructive airways disease. Informed consent and tissue acquisition were performed according to protocols approved by the Institutional Review Board at UCDMC and the University of Manitoba.