Human lung mucous glands manifest evidence of the H+/K+-ATPase proton pump

Objectives: The H+/K+-ATPase proton pump has been demonstrated in human laryngeal submucosal glands, and is not solely present in the parietal cells of the stomach. Although proton secretion is present in the lung, a variety of mechanisms have been elucidated. The hypothesis of this study is that the H+/K+-ATPase proton pump is one additional pathway of proton secretion in the human lung. Methods: Fourteen surgical lung specimens from 10 subjects were retrospectively obtained after approval from our Human Subjects Committee. Banked human stomach tissue was used for comparative positive and negative controls. Sections were immunostained with 2 monoclonal antibodies selectively reactive with alpha or beta subunits of the H+/K+-ATPase proton pump. Results: In the human lung, consistent staining for both subunits was present in the mucous gland cells and ducts in all specimens in which mucous glands were present (6 specimens from 5 subjects). Overall, weak to strong staining was present in focal areas within the multicellular mucous glands. There was only scant focal staining in the respiratory epithelium in 4 specimens. Stomach parietal cells exhibited strongly positive staining for both subunits of the proton pump. There was no staining in stomach cells that were not morphologically consistent with parietal cells. Conclusions: The H+/K+-ATPase proton pump is present in mucous cells and ducts in the human lung, with some variable expression noted. Proton pump inhibitor pharmacotherapy may have a site of action in the human lung, explaining some of the controversies otherwise attributable to interrelatedness of aerodigestive tract disease.