Neutrophil specific granule deficiency.

Neutrophil specific granules are thought to be important in the evolution of the inflammatory response. Specific granules are preferentially released with minor membrane perturbation in vitro or in vivo, and secreted products probably have important effects on humoral and cellular components of inflammation. In vitro studies reveal that some secreted specific granule products activate the complement cascade to generate the chemoattractant C5a and the opsonin C3b, while other secreted products are selectively chemotactic for monocytes. Translocation of receptors for chemoattractants (fmet-leu-phe) and opsonins (C3bi) from specific granules or closely related organelles to the plasma membrane may play an important role in chemotaxis, adherence, and phagocytosis. Similar translocation of constituents of the electron transport chain involved in the respiratory burst (i.e. cytochrome b) probably plays a role in neutrophil oxidative metabolism and hydrogen peroxide generation. In vivo and in vitro studies of neutrophils from patients with congenital specific granule deficiency, acquired specific granule deficiency (thermal injury and neonates), or normal neutrophils experimentally depleted of nuclei and organelles support these conclusions. Thus, release of specific granule constituents appears to be important for amplification of the initial and subsequent phases of the inflammatory response.