 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.imagesfigure 4 . 
 afigure 4 . 
 bfigure 4 . 
 cfigure 4 . 
 d 
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