Phagolysosomal morphology and dissolution of cobalt oxide particles by human and rabbit alveolar macrophages

The effect of phagolysosomal size on dissolution of cobalt oxide particles was evaluated in two different macrophage systems: alveolar macrophages (AM) of human smokers with phagolysosomes enlarged by ingested cigarette smoke products, and rabbit AM incubated in vitro with sucrose, which causes swelling of the phagolysosomes by osmosis. Human AM from smokers and nonsmokers were studied in vitro. There was no significant difference in particle dissolution between AM obtained from smokers and nonsmokers, although there was a clear difference in the morphological appearance of AM, including significantly larger phagolysosomes in smokers. Rabbit AM were incubated for 24 or 72 h with or without 80 mM sucrose in the medium. The sucrose-treated cells had 3-4 times larger phagolysosomes than untreated cells, with no major change in phagolysosomal pH. The increased size of the phagolysosomes did not affect the ability of the AM to dissolve cobalt oxide particles. Furthermore, rabbit AM showed the same ability as human AM to dissolve the cobalt oxide particles, in spite of the fact that they had markedly smaller phagolysosomes. Another difference between human and rabbit AM was that phagolysosomes in human AMs increased in size with time in culture, while rabbit AM phagolysosomes decreased in size.