Levels of Surfactant Proteins A and D and KL-6 Are Elevated in the Induced Sputum of Chronic Obstructive Pulmonary Disease Patients: A Sequential Sputum Analysis

Background: Recent clinical studies have suggested that serum surfactant protein (SP) A, SP-D and Krebs von den Lungen-6 (KL-6) are potential biomarkers for interstitial lung diseases. Serum levels of SP-A and SP-D have also been found to be elevated in chronic obstructive pulmonary disease (COPD), but their significance has not been evaluated or compared in induced sputum samples obtained directly from the airways. Objective: A sequential sputum analysis was conducted to assess the value of SP-A, SP-D and KL-6 levels in COPD. Methods: The study material consisted of induced sputum samples from 61 subjects, 28 with COPD and 33 with prolonged cough (cough lasting 1 3 weeks and normal spirometry). Sputum was collected in 3 fractions (3 periods of 5 min each). Sputum levels of these proteins were measured, and receiver operating characteristic curve analysis was carried out to evaluate the sensitivity, specificity and area under the curve (AUC) for each fraction. Results: The levels of SP-A, SP-D and KL-6 were higher in patients with Received: June 22, 2010 Accepted after revision: January 24, 2011 Published online: April 7, 2011 Noboru Hattori Department of Molecular and Internal Medicine Graduate School of Biomedical Sciences, Hiroshima University 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551 (Japan) Tel. +81 82 257 5196, E-Mail nhattori @ hiroshima-u.ac.jp © 2011 S. Karger AG, Basel 0025–7931/11/0821–0010$38.00/0 Accessible online at: www.karger.com/res D ow nl oa de d by : 54 .7 0. 40 .1 1 11 /1 9/ 20 17 2 :2 6: 34 P M