Reverse relationship between lysosomal-enzyme release and active-oxygen generation in stimulated human neutrophils

The relationship between the generation of active species of oxygen (O-2, H2O2 and OH.), chemiluminescence, and the release of lysosomal enzymes (lysozyme, alpha-mannosidase and beta-glucuronidase) was examined in human neutrophils stimulated with opsonized zymosan in the presence or absence of active-oxygen scavengers. In the absence of scavengers, increasing zymosan concn stimulated a marked increase in active-oxygen production in a concn-dependent manner and a less rigorously dose-dependent increase in enzyme secretion. Addition of OH. and/or 1O2 scavengers (benzoate, 1,4-diazo-bicyclo-2,2,2-octane or xanthine) caused a marked increase in enzyme release and a decrease in the generation of active-oxygen species except O-2 and H2O2. These findings suggest that exocytosis of lysosomal enzymes by stimulated neutrophils might be attenuated by the active generation of OH. and chemiluminescence. Superoxide dismutase (SOD) at low concns inhibited lysosomal enzyme release while promoting OH formation; and SOD at high concns decreased OH. and O-2 formation and chemiluminescence, accompanied by higher levels of lysosomal enzyme release. Catalase showed an effect similar to that of SOD. Our data suggest that the reduction by scavengers of active-oxygen levels, particularly of the species detected in the OH. and chemiluminescence assays, results in an increase in lysosomal enzyme release.