Opsonized zymosan decreases cytoplasmic motility of alveolar macrophages in dogs

Abstract

To examine the mechanisms of changes in alveolar macrophage (AM) activities caused by phagocytic stimulus, we studied the effect of opsonized zymosan (OZ) on cytoplasmic motility (CM) of AM from dog lungs in vitro. Four days after the installation of ferrimagnetic particles (Fe 3O 4, 3 mg/kg) into the lower lobe bronchus, AM were harvested by broncho-alveolar lavage. AM were adhered to the bottom of plastic vials (10 6 cells of AM per each vial). Remanent field strength (RFS) from the AM containing Fe 3O 4 particles was measured immediately after magnetization. RFS decreased with time due to particle rotation (relaxation), which is related to cytoplasmic motility of AM. OZ (1–500 μg) decreased λ 0 (the relaxation rate for the first min) in a concentration-dependent fashion. Neither BW755C (10 −5 M), indomethacin (10 −6 M), leupeptin (10 −5 M), nor superoxide dismutase (1000 U/ml) inhibited OZ (500 μg)-induced inhibitory effects on λ 0, suggesting that cyclooxygenase and lipoxygenase products, serine, thiol enzymes, aminopeptidase and superoxide anion were not responsible for OZ-induced effects. OZ (500 μg) significantly increased the intracellular concentration of Ca 2+ ( sP < 0.01), Likewise, OZ (500 μg)-induced effects on λ 0 of AM were significantly inhibited by replacement of the medium with a Ca 2+ free solution ( P < 0/01). These results imply that opsonized zymosan inhibits cytoplasmic motility of AM via external calcium influx.