Loss of cathepsin B activity in alveolar macrophages after in vitro quartz phagocytosis.
Bovine alveolar macrophages were incubated up to 20 h with DQ12 quartz particles, either in untreated native form or pretreated with dipalmitoyl lecithin. The content of cathepsin B and N-acetylglucosaminidase was measured in the culture supernatant and in the cells. After incubation, a loss of about 50% of the total cathepsin B activity in the culture dish was observed, whereas no influence on total N-acetylglucosaminidase content occurred. Loss of cathepsin B activity was completely prevented by the pretreatment of quartz with the surfactant component dipalmitoyl lecithin. Similarly, a complete abrogation of the quartz effect on cathepsin B was noted when the cells were incubated with quartz in the presence of NH4Cl in order to prevent phagosome-lysosome fusion. There was also no influence on cathepsin B activity when a lysosome-rich fraction, prepared from alveolar macrophages, was incubated together with quartz. It was concluded that the reduction of cathepsin B activity was related with the intralysosomal deposition of quartz particles.
Pätzold
S
S
Kernforschungszentrum Karlsruhe, Institut für Toxikologie, Germany.
Schmidt
A
A
Seidel
A
A
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000494:pharmacology; D000118:Acetylglucosaminidase / Q000378:metabolism; D000818:Animals; D002401:Cathepsin B / Q000378:metabolism*; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D010587:Phagocytosis; D011791:Quartz / Q000276:immunology / Q000633:toxicity*
D011791:Quartz; D015060:1,2-Dipalmitoylphosphatidylcholine; D000118:Acetylglucosaminidase; D002401:Cathepsin B