Human alveolar macrophages: comparison of cell size, autofluorescence, and HLA-DR antigen expression in smokers and nonsmokers.

To investigate the influence of cigarette smoking on alveolar macrophages (AM) we compared morphologic and immunocytochemic characteristics of bronchoalveolar lavage cells collected from 10 smokers and 8 nonsmokers. AM were studied using single cell fluorescence photometry. AM of smokers were larger in size (p < 0.001), showed stronger autofluorescence (p < 0.001), and expressed fewer HLA-DR antigens (p < 0.001) compared with AM of nonsmokers. AM of smokers were more heterogeneous in respect to cell size, autofluorescence, and HLA-DR antigen expression. HLA-DR antigen density on AM of smokers was independent of cell size and autofluorescence. This suggests that tobacco smoke reduces HLA-DR antigen expression in AM of different maturational states and that this defective expression of HLA class II antigens is not dependent on the amount of phagocytosed autofluorescent tobacco particles.