Comparison of human lung surface protein profiles from the central and peripheral airways sampled using two regional lavage techniques

This study describes two new techniques of lung lavage which selectively remove material from the central airways, or from the lung below the seventh generation. Bronchograms confirmed that discrete regions of the lung were washed by central lavage (CL; maximum airway diameter approximately 6.5 mm) and peripheral lavage (PL; maximum airway diameter approximately 1.3 mm), and that both could be clearly distinguished from conventional bronchoalveolar lavage (BAL). These techniques were used to establish whether or not large-airway proteins made a major contribution to the protein profile of BAL. Twenty consecutive patients undergoing routine fibreoptic bronchoscopy were investigated. More bronchial mucus proteinase inhibitor per unit albumin and per unit total measured antiproteinase was present in CL than PL or BAL. In contrast alpha 1-proteinase inhibitor per unit albumin and as a percentage of total measured antiproteinase was lower in CL than in other lavage types. There were no differences in elastase activity, irrespective of the way in which the data were expressed. As no differences were found between BAL and PL for any of the variables measured, it was concluded that in the subjects studied the contribution of CL proteins to BAL was minimal.