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In biology, a phagolysosome, or endolysosome, is a cytoplasmic body formed by the fusion of a phagosome with a lysosome in a process that occurs during phagocytosis. Formation of phagolysosomes is essential for the intracellular destruction of microorganisms and pathogens .
Phagocytosis of a bacterium, showing the formation of phagosome and phagolysosome. In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs). [1]
The phagosome is the organelle formed by phagocytosis of material. It then moves toward the centrosome of the phagocyte and is fused with lysosomes, forming a phagolysosome and leading to degradation. Progressively, the phagolysosome is acidified, activating degradative enzymes. [10] [15] Degradation can be oxygen-dependent or oxygen-independent.
This is the fusion of granules with the phagolysosome, releasing their contents, including myeloperoxidase. [10] As many microbicidal products are formed during respiratory burst, the importance of individual molecules in killing invading pathogens is not wholly understood.
Once a pathogen has been engulfed by a phagocyte, it becomes trapped in an intracellular vesicle called a phagosome, which subsequently fuses with another vesicle called a lysosome to form a phagolysosome. The pathogen is killed by the activity of digestive enzymes or following a respiratory burst that releases free radicals into the phagolysosome.
Some bacteria are capable of living inside of the phagolysosome. Staphylococcus aureus , for example, produces the enzymes catalase and superoxide dismutase , which break down chemicals—such as hydrogen peroxide—produced by phagocytes to kill bacteria. [ 119 ]
CHS is a disease causing impaired bacteriolysis due to failure of phagolysosome formation. [8] As a result of disordered intracellular trafficking there is impaired lysosome degranulation with phagosomes, so phagocytosed bacteria are not destroyed by the lysosome's enzymes. [citation needed]
Within the phagolysosome, enzymes and toxic peroxides digest the pathogen. However, some bacteria, such as Mycobacterium tuberculosis , have become resistant to these methods of digestion. Typhoidal Salmonellae induce their own phagocytosis by host macrophages in vivo, and inhibit digestion by lysosomal action, thereby using macrophages for ...