The enzymatic removal of a surfactant coating from quartz and kaolin by P388D1 vells.
Hill-CA; Wallace-WE; Keane-MJ; Mike-PS
Cell Biol Toxicol 1995 Apr; 11(2):119-128
A study was conducted examining the ability of macrophages to remove a dipalmitoyl-phosphatidylcholine(DPL) coating from the surface of particles. The P388D1 macrophage cell line was incubated with DPL coated quartz (14808607) and kaolin (1332587) particles and the removal of DPL was examined for up to 9 days. P388D1 digested DPL from the surface of both quartz and kaolin particles at a rate that was independent of the dust concentration and of the amount of coated dust within the cell at lower concentration levels. The rate of digestion decreased slightly at the highest concentration of dust used. These results were suggestive of extracellular phospholipase activity. Characterization of the extracellular phospholipase activity demonstrated that it was inhibited by increasing temperatures, chlorphentermine, imipramine, chloroquine, ethylenediaminetetraacetic-acid, decreasing pH, and pretreatment with proteinase-K or trypsin, and unaffected by freezing and thawing. These characteristics were consistent with an extralysosomal phospholipase active at pH7 and dependent upon the presence of divalent metal ions. The rate of DPL removal by the extracellular phospholipase from kaolin was slower than the rate of removal from quartz.
NIOSH-Author; Quartz-dust; In-vitro-study; Surfactants; Enzyme-activity; Dose-response; Pulmonary-system; Metallic-ions
Cell Biology and Toxicology