DEFENSINS IN GRANULES OF PHAGOCYTIC AND NON-PHAGOCYTIC CELLS

Antimicrobial proteins stored in lysosome-like granules of neutrophils and macrophages probably play an important role in killing phagocytos ed microbes after delivery to the phagolysosome. Among the granules' a ntimicrobial armamentarium are defensins, peptides that kill a broad s pectrum of microorganisms in vitro. Antimicrobial defensins were recen tly also isolated from non-phagocytic granulocytes of the mouse small intestinal epithelium, from where they are secreted into the lumen to function extracellularly. Clarification of the antimicrobial mechanism s of defensins in intracellular and extracellular environments will pr ovide a key to understanding peptide-mediated host defence.