Late-breaking abstract: Repeated analysis of alpha-1-antitrypsin concentrations in sputum, lavage and serum of smokers with and without COPD

Introduction: Alpha-1-antitrypsin (A1AT)-deficiency is a hereditary disease that can lead to the development of emphysema. Serum levels of A1AT are used for diagnosis and monitoring during substitution therapy. Aim: We have previously shown that A1AT levels differ between smokers with and without COPD (Roepcke et al. ERS2010). Here we assessed the repeatability of A1AT levels in serum, induced sputum (IS) and bronchoalveolar lavage (BAL) over a period of 6 weeks and compared the concentrations between compartments. Methods: 24 COPD patients (GOLD II) and 23 age and gender matched healthy controls were included into the study. All were current smokers (≥ ten pack-years). Blood, BAL, and IS were collected on two occasions. A1AT was analyzed by ELISA, CRP by Luminex. Results: The median (IQR) A1AT concentrations was 1.69 (0.53) g/L in serum, 505 (596) μg/L in BAL and 568 (475) μg/L in IS. The reproducibility between visits within each matrix was good (serum: r=0.55, p Conclusion: A1AT appears to be stable within compartments in healthy smokers and smokers with moderate COPD. The lack of relationship between lung and serum A1AT should be considered when interpreting serum A1AT for diagnostic and monitoring purposes.