Alveolar phagocyte

Fig. 118. Beginning of the formation of a multinucleate giant cell by fusion of mononuclear alveolar phagocytes. Female white rat (breeder Winkelmann, Borchen-Kirchborchen) medicated with 125 mg dexpanthenol in a 5 % aqueous solution per kg body weight x day during a 5-day work week. Oral application took place from April 17 to August 14, 1967 for a total of 82 days. Fixed on August 14, 1967 under methi-tural anaesthesia by intratracheal instillation of 2.5 % gluta-raldehyde in phosphate buffer (pH 7.4) before opening the thorax. Postfixation with 1 % osmium tetroxide in phosphate buffer (pH 7.4). Contrasted en bloc for 12 h with 0.5 % uranyl acetate in 70% ethanol. Embedded in a 2 8 mixture of methyl and butyl methacrylate. Sectioned at 50 nm. Lead citrate after Reynolds (1963). Plate 5/05...

Alveolar lumina completely filled with phagocytes some of which have been destroyed were found in a 38 years old patient, who had worked in a titanium dioxide factory for about nine years, all this time as a repair worker in the dusty departments (Elo et al. 1972). Specimens from this and another patient showed alveolar phagocytes with large lyso-somes containing electron-dense Ti02 particles. 

In vivo studies showed that in vitro proliferation of lymphocytes isolated from marijuana smokers is suppressed, especially with heavy marijuana smoking, and that the relative proportion of lymphocyte subpopulations was also altered. Concentrations of serum IgG are decreased and IgE concentrations are increased in marijuana smokers. Furthermore, phagocytic and bactericidal activity of alveolar macrophages from heavy marijuana smokers are decreased. These effects translate into reduced host resistance following administration of cannabinoids, including THC, in both humans and animals (Table 30.2). Increased susceptibility has been demonstrated to opportunistic microbes including HIV, Herpes simplex virus, Friend leukemia virus Listeria, Treponema pallidum, and Legionella. 

Interest in the effects of ozone on alveolar macrophages has been spurred by the observation that relatively low concentrations of ozone potentiate respiratory infections in animals and perhaps man. Coffin et al ob-ser a decrease in the number of bacteria phagocytized by alveolar macrophages obtained from rabbits exposed to various concentrations of ozone as low as 0.3 ppm. Some suggestion of a lack of threshold is present, but it is not clear whether the difference from the controls at lower ozone concentrations is statistically significant. 

Particles deposited on or in the lung parenchyma are cleared primarily by alveolar macrophages. These phagocytized particles migrate to the ciliated epithelium or to the... 

At the distal respiratory site, the alveolar epithelial cell layer is much flatter (0.1 -0.5 pm) and composed of two major cell types, squamous type I and agranular type II pneumocytes. Type I pneumocytes are non-phagocytic and highly flattened cells with broad and thin extensions. They occupy -95 % of the alveolar luminal surface, although they are less numerous than type II cells. The remaining surface is occupied by type II pneumocytes, which have blunt microvilli and contain multivesicular bodies [3, 11]. 

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