Identification of lipocalin and apolipoprotein A1 as biomarkers of chronic obstructive pulmonary disease.

Rationale: Much effort is being made to discover noninvasive biomarkers of chronic airway disease that might enable better management, predict prognosis, and provide new therapeutic targets.

Objectives: To undertake a comprehensive, unbiased proteomic analysis of induced sputum and identify novel noninvasive biomarkers for chronic obstructive pulmonary disease (COPD).

Methods: Induced sputum was obtained from patients with COPD with a spectrum of disease severity and from control subjects.