Plasmacytoid monocytes appear in the bronchoalveolar lavage: differences between smokers and nonsmokers

The primary purpose of this study was to describe the expression pattern of the surface antigens CD68, CD36, 27E10, G16/1, and RM3/1 on bronchoalveolar lavage (BAL) cells of smokers and nonsmokers. We found a cell type, morphologically similar to lymphocytes, which showed a strong expression of the monocyte markers CD68 and CD36. We therefore recognized these cells as plasmacytoid monocytes (PM). Hereby we report the appearance of PM in the BAL and its dependency of smoking. The study was conducted in 40 patients with various lung diseases and normal subjects. Sixteen patients and normal subjects were smokers and 24 were nonsmokers. There was a significant increase of PM in the BAL of smokers compared to nonsmokers. However we could not find a disease-related increase of PM in the BAL. This is the first report demonstrating the occurrence of PM in the BAL. Our data support the monocytic origin of PM and suggest an involvement in T cell-mediated responses of the lung.