Cytochalasin B-dependent release of azurophil granule enzymes from human polymorphonuclear leukocytes

The dose-response effects of phorbol myristate acetate and cytochalasin B on secretion of azurophil and specific granule enzymes from viable human polymorphonuclear leukocytes have been examined. Secretion of the azurophil granule enzymes elastase and beta-glucuronidase from cells exposed to 50 ng/ml of phorbol myristate acetate is dependent on prior exposure of the cells to greater than 0.5 mg/ml of cytochalasin B. In contrast, the secretion of the specific granule enzyme lysozyme is not dependent on pretreatment with cytochalasin B. The concentration of phorbol myristate acetate needed to elicit maximal secretion of specific versus azurophil granule enzymes differs, being 5.0 ng/ml and 50 ng/ml, respectively. The results suggest that cytochalasin B-sensitive cellular components, possibly microfilaments, may selectively modulate some step in the exocytosis of azurophil granule enzymes from human polymorphonuclear leukocytes exposed to phorbol myristate acetate.