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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 .
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 ...
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.
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.
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).
The autophagic process is divided into five distinct stages: Initiation, phagophore nucleation, autophagosomal formation (elongation), autophagosome-lysosome fusion (autophagolysosome) and cargo degradation.
The phagosome then combines with a lysosome to create a phagolysosome. In the phagolysosome, the cell attempts to use reactive oxygen species and acid to kill the bacterium. However, M. tuberculosis has a thick, waxy mycolic acid capsule that protects it from these toxic substances.
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 .