DRAMATIC morphologic changes occur in polymorphonuclear leukocytes during bacterial phagocytosis. Cytoplasmic granules disappear, and the granular membranes fuse with phagocytic vacuoles. These granules (lysosomes) containing hydrolytic enzymes and cationic proteins with specific antimicrobial properties are solubilized during phagocytosis and surround the bacteria in phagocytic vacuoles. Despite identification of bactericidal factors (for example, muramidase and phagocytin) and knowledge of their shift to the phagocytic vacuole, the functional mechanism of intracellular bacterial killing is still uncertain. Peritoneal mononuclear leukocytes without muramidase or phagocytin are able to kill bacteria rapidly, and in a reverse situation, polymorphonuclear leukocytes from patients with chronic granulomatous disease . . .