Exocytosis of neutrophil granulocytes

Neutrophil granulocytes play an important role in the defense mechanisms of mammalian organisms against bacterial invaders. The combat arsenal of neut rophils consists of engulfing and endocytosing the foreign particle, produc ing toxic oxygen compounds, and liberating substances stored in intracellul ar vesicles. At least four different types of granules are formed during ma turation of neutrophil granulocytes in the bone marrow. Functional properti es of release from the different granule populations differ in several resp ects from characteristics of neurotransmitter release, the best understood secretory process in mammals. The available data indicate that several key proteins of the exocytotic machinery identified in neural tissue either are absent from neutrophil granulocytes or their subcellular localization is d ifferent. Furthermore, in a human disease (Chediak-Higashi syndrome), the d efect of the secretory pathway affects mainly the cells of the haemopoietic lineage. Taken together, these data suggest that regulated exocytosis from neutrophil granulocytes (or perhaps also from other haemopoietic cells) ma y represent a specific case of the general mechanism of secretion. BIOCHEM PHARMACOL 57;11:1209-1214, 1999. (C) 1999 Elsevier Science Inc.