The activation of phospholipase A in macrophages after the phagocytosis of silica and other cytotoxic dusts.
The phospholipid and lipid metabolism of mouse peritoneal macrophages has been studied in the presence of various silicogenic dusts and asbestos particles. These extensive kinetic studies were possible as a reproducible method was developed to determine these major cellular constituents after labelling macrophages with 1-14C-oleic acid. The following results have been obtained so far: 1. Silicogenic dusts activate a phospholipase A in macrophages leading to a concentration and time-dependent degradation of lecithin and cephalin. 2. Using low doses of SiO2 (less than 1 mg/10(7) cells) the split-off free fatty acid can still be transesterified into the triglycerides. 3. High doses of silica (greater than 2 mg/10(7) cells) induce also a lipolysis. 4. Silica specifically inhibits a plasma membrane-bound acyltransferase 5. Asbestos particles induce in long-term cultures a moderate degradation of diacylphospholipids with transesterification of 1-14C-oleic acid into the triglycerides.
D000818:Animals; D001194:Asbestos; D001202:Ascitic Fluid / Q000166:cytology; D004391:Dust; D004789:Enzyme Activation; D066298:In Vitro Techniques; D008264:Macrophages / Q000201:enzymology / Q000502:physiology*; D051379:Mice; D010587:Phagocytosis; D010740:Phospholipases / Q000378:metabolism*; D012822:Silicon Dioxide
D004391:Dust; D001194:Asbestos; D012822:Silicon Dioxide; D010740:Phospholipases