FIG. 1.

Fusion of azurophil granules with phagosomes in neutrophils is triggered by IgG opsonization of M. smegmatis. (A) Neutrophils were incubated with immune serum-opsonized zymosan (OZ) (20 particles per cell) for 20 min or with live, heat-killed or immune serum-opsonized M. smegmatis for 40 min (50 particle per cell). The release of the lysosomal enzyme β-glucuronidase was measured. Results are expressed as means + SDs (error bars) of three experiments. ∗∗∗, P < 0.001 versus control; ○○○, P < 0.001 versus M. smegmatis. (B) M. smegmatis was grown for different periods of time (in days [D]), and the growth was monitored by measuring the optical density at 650 nm and the cell wet weight (insert). Neutrophils were incubated with M. smegmatis collected at different growth stages, and the release of β-glucuronidase was measured. OZ was used to show the level of β-glucuronidase released when lysosomal degranulation is triggered. Results are expressed as means + SDs (error bars) of three experiments. ∗, P < 0.05 versus control.