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 instillation of ferrimagnetic particles (Fe3O4, 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 Fe3O4 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-mu-g) decreased lambda-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), bestatin (10(-5) M), nor superoxide dismutase (1000 U/ml) inhibited (500-mu-g)-induced inhibitory effects on lambda-0, suggesting that cyclooxygenase and lipoxygenase products, serine, thiol enzymes, aminopeptidase and superoxide anion were not responsible for OZ-induced effects. OZ (500-mu-g) significantly increased the intracellular concentration of Ca2+ (P < 0.01). Likewise, OZ (500-mu-g-induced effects on lambda-0 of AM were significantly inhibited by replacement of the medium with a Ca2+ free solution (P < 0.01). These results imply that opsonized zymosan inhibits cytoplasmic motility of AM via external calcium influx.
