Influence of surfactant components and exposure geometry on the effects of quartz and asbestos on alveolar macrophages.

Bovine (BAM) and rat (RAM) alveolar macrophages were incubated in vitro with DQ12 quartz or UICC chrysotile asbestos either alone or in the presence of dipalmitoyl lecithin (DPL). The reaction of the cells of both species to the untreated dust particles was similar qualitatively and quantitatively, with a loss of viability and release of lactate dehydrogenase and N-acetyl-beta-glucosaminidase after 20 hr of incubation. In the presence of DPL, the toxicity of quartz to BAM disappeared completely, whereas the protective influence of the phospholipid was distinctly diminished in the case of RAM. The presence of lavage fluid was less effective than that of pure DPL. There was no protective influence of DPL with asbestos either for BAM or for RAM. The effects of phagocytizable, suspended quartz particles were compared with the effects of the same type of particles fixed on a glass surface to exclude the possibility of phagocytosis. The effect of the suspended particles on the viability and release of enzymes was more pronounced than that of the fixed particles. On the other hand, superoxide anion production was stimulated to a much higher degree by the fixed quartz particles. This could be explained by the continuing contact of the outer cell membrane with the silica surfaces, whereas free particles were rapidly phagocytized. The release of lysosomal enzymes induced by fixed quartz particles was a secondary phenomenon following cell death.