Fagossomolisossomo

Fagossomolisossomo is the organelle formed when a phagosome fuses with a lysosome during phagocytosis. In phagocytic cells such as macrophages and neutrophils, engulfed particles are enclosed in a membrane-bound phagosome that matures and merges with lysosomes to create the phagolysosome. The phagolysosome provides an acidic environment and delivers a full complement of lysosomal hydrolases that degrade proteins, lipids, nucleic acids, and other macromolecules.

In addition to digestion, the phagolysosome hosts antimicrobial mechanisms, including the production of reactive oxygen species and reactive nitrogen species, and, in certain cell types, the activity of enzymes such as myeloperoxidase that contribute to microbial killing. The maturation and fusion process is tightly controlled and involves Rab GTPases, SNARE proteins, and tethering factors; acidification is driven by proton pumps (V-ATPases) that lower the internal pH to optimize enzyme activity.

Functionally, the fagossomolisossomo is central to innate immunity by eliminating internalized pathogens and debris and by processing sample antigens for presentation on MHC class II molecules in antigen-presenting cells. Some pathogens, including Mycobacterium tuberculosis, have evolved strategies to inhibit phagosome-lysosome fusion to survive within host cells, highlighting the importance of this fusion event in host defense.

Clinical relevance includes the potential consequences of defective phagosome-lysosome fusion or lysosomal dysfunction, which can compromise microbial killing and contribute to immunodeficiency and lysosome-related disorders.