Fagolüsosoom

Fagolüsosoom, or phagolysosome, is a membrane-bound organelle found in phagocytic cells such as macrophages, neutrophils, and dendritic cells. It forms when a phagosome, which contains material ingested by the cell, fuses with a lysosome. The resulting compartment combines hydrolytic enzymes from the lysosome with the ingested material for degradation.

During the phagolysosome formation, the phagosome matures through interactions with endosomal compartments and signaling pathways that regulate its trafficking and fusion. The interior becomes highly acidic, and a range of degradative enzymes, including proteases, lipases, nucleases, and glycosidases, breaks down proteins, lipids, nucleic acids, and carbohydrates. Reactive oxygen species and antimicrobial peptides generated within the phagolysosome contribute to microbial killing and digestion. In many phagocytes, the phagolysosome also participates in processing peptides for presentation on MHC class II molecules, aiding the adaptive immune response.

Fagolüsosooms play a central role in innate immunity by clearing pathogens and debris and in antigen processing. Some pathogens have evolved strategies to avoid phagolysosome fusion or to resist its degradative environment, which can influence the outcome of infections. Beyond host defense, phagolysosomes are involved in tissue homeostasis and the resolution of inflammation. Their function is studied in immunology, cell biology, and infectious disease research to understand how cells balance destruction of ingested material with antigen presentation and immune signaling.