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

Abstract

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.

The acute effect of cigarette smoking on the neutrophil elastase inhibitory capacity of peripheral lung lavage from asymptomatic volunteers

“…The percentage of instilled fluid recovered before smoking was approximately 30% and did not differ after cigarette smoke exposure (table 2). Similarly, the cell numbers and profiles were within the normal range for this laboratory [15], with the exception of one subject (subject 4) who had above normal levels of polymorphonuclear neutrophils both before and after smoking (7 and 11%, respectively). Eosinophils were detected in the second lavage of two of the subjects (1% and 2% of the total cell number; subjects 6 and 2, respectively).…”

“…A possible explanation for the low BI/albumin values obtained in this study compared to those obtained by ABRAMS et al [29) is that peripheral lavage is not analogous to BALF, which contains proteins from large airways [14]. Thus, hypersecretion by the airways of some smokers could significantly elevate the levels of BI in BALF but not in PLF [14,15). The level of bronchial inhibitors measured in lung washings and sputum may also depend on the clinical status of the subject [29,32] and it has been hypothesized that there may be genetic variability between individuals in the levels of bronchial inhibitors [34).…”

“…The differences between the levels of PI before and after smoking might have been caused by the first bronchoscopy and lung lavage or may reflect normal differences between contralateral lobes; we could not investigate this as the volunteers were not prepared to undergo a sham smoking study. However, we think it unlikely as, in a previous study comparing peripheral and bronchoalveolar lavage from patients, we found no differences in the PI or BI to albumin ratio in lavage from contralateral lungs or between consecutive lavages [15). PI is thought to diffuse freely across the pulmonary interstitium alongside albumin [27), which was by convention used to standardize this data [27].…”

“…An Olympus BF 1 T bronchoscope was wedged at the third or fourth airway generation of the left upper lobe. A double lumen, 6F balloon-tipped catheter was passed through the biopsy channel and extended up to 5 cm beyond the Lip of the bronchoscope to enable lavage of airways peripheral to the 7th generation as previously described [14,15). Following secure wedging of the inflated balloon, five separate 20 ml aliquots of warmed, sterile sodium chloride solution (0.15 M) were introduced and aspirated from lhe lower respiratory tract of a single bronc hopulmonary segment.…”

“…Little is known about the role of the bronchial inhibitors in the protection of the lung from emphysema. In patients, lavage obtained from the peripheral lung (below the 7th airway generation) using a selective lavage technique contains BI [14,15] and this, together with the observation that there is BI present in the secretory granules of the Clara cells in the terminal and respiratory bronchioles [16], where emphysema in smokers often begins, suggests that BI and possibly other inhibitors may play a significant role in the protection of peripheral lung tissue from elastolysis and emphysema.…”