Human airway macrophages. A technique for their retrieval and a descriptive comparison with alveolar macrophages

We developed a technique to isolate and lavage a segment of a large human airway in vivo. Airway lavage and BAL were performed without significant complications 18 times on 17 normal volunteers. The mean +/- SEM volume of instillate used on all subjects totaled 31.3 +/- 2.7 ml with 47.1 +/- 3.8% of the fluid recovered. A total of 1.5 +/- 0.3 x 10(6) cells were retrieved. Cell viability averaged 71.3 +/- 4.6%. The majority of the cells were macrophages, 27.9 +/- 2.7%, and neutrophils, 28.4 +/- 6.0%. A descriptive comparison of airway macrophages using transmission electron microscopy with those retrieved from paired bronchoalveolar lavage (BAL) samples revealed that airway macrophages possessed more vacuoles (p less than 0.0001), fewer long microvilli (p less than 0.0001), and more membrane undulations (p less than 0.0001). In contrast, macrophages from both lavage locations demonstrated similar staining characteristics when stained with a panel of monoclonal antibodies. During lavage, all subjects experienced mild dyspnea that was relieved when the lavage was completed. One of three subjects tested during the procedure revealed O2 desaturation that was prevented by the inhalation of O2. We conclude that viable macrophages can be retrieved safely from airways of normal subjects and that, compared with macrophages present in BAL, these cells bear both similarities and dissimilarities that may portend differing functional capabilities.