RT Journal Article SR Electronic T1 Lung secretion sol-phase proteins: comparison of sputum with secretions obtained by direct sampling. JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 102 OP 107 DO 10.1136/thx.38.2.102 VO 38 IS 2 A1 J Wiggins A1 S L Hill A1 R A Stockley YR 1983 UL http://thorax.bmj.com/content/38/2/102.abstract AB The protein content of tracheal secretions and of bronchial lavage and bronchoalveolar lavage fluid was compared with that of sputum in 33 patients who underwent fibreoptic bronchoscopy. The secretion-to-serum concentration ratios for albumin, alpha 1-antitrypsin, alpha 1-antichymotrypsin, and immunoglobulin A (IgA) fell progressively as samples were obtained from further down the bronchial tree, probably reflecting greater sample dilution. The secretion-to-serum protein ratios when standardised for the corresponding albumin ratio were similar in all secretions studied. In particular, the IgA ratios were about eight times those of albumin and alpha 1-antichymotrypsin ratios were about twice those of albumin, suggesting similar degrees of "local production" of these proteins in all secretions studied. Some patients showed considerable differences in IgA ratios between sputum and bronchial lavage fluid. The significance of these differences is not clear.