title: The effects of intratracheally administered coarse mode particles on respiratory tract infection in mice.
abstract: Because coarse mode particles are rarely studied in their existing size ranges (greatest mass about 5-7 microns, aerodynamic diameter), we investigated the effects of four such particles, quartz, ferric oxide, calcium carbonate, and sodium feldspar, on host defenses against bacterial pulmonary infection. Mice which received intratracheal instillations of 10, 33, and 100 micrograms/mouse were exposed within an hour to aerosols of viable Streptococcus, and pneumonia-induced mortality was measured. At 33 and 100 micrograms/mouse, all particles significantly increased mortality. At the lower dose, only Fe2O3 caused a significant increase in mortality. To evaluate potential delayed effects, mice were challenged with the bacteria 24 h after exposure to 100 micrograms particles/mouse. Delaying the challenge did not significantly alter the response, except for the sodium feldspar group for which a partial recovery was observed. When mice exposed to 100 micrograms particles/mouse received aerosols of Klebsiella pneumoniae 24 h later, there was no significant effect on pulmonary bactericidal activity. For the model system used, it appears that Fe2O3, CaCO3, and sodium feldspar have effects roughly equivalent to quartz.
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D005260:Female; D007113:Immunity, Innate / Q000187:drug effects; D007442:Intubation, Intratracheal; D051379:Mice; D010316:Particle Size; D012141:Respiratory Tract Infections / Q000209:etiology* / Q000276:immunology
chemical_list: D000336:Aerosols; D000393:Air Pollutants