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Phagocytosis (from Ancient Greek φαγεῖν (phagein) 'to eat' and κύτος (kytos) 'cell') is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called a phagocyte.
The first demonstration of phagocytosis as a property of leukocytes, the immune cells, was from the German zoologist Ernst Haeckel. [14] [15] In 1846, English physician Thomas Wharton Jones had discovered that a group of leucocytes, which he called "granule-cell" (later renamed and identified as eosinophil [16]), could change shape, the phenomenon later called amoeboid movement.
Unbound phagocyte surface receptors do not trigger phagocytosis. 2. Binding of receptors causes them to cluster. 3. Phagocytosis is triggered and the particle is taken up by the phagocyte. Phagocytosis is the process of taking in particles such as bacteria, invasive fungi, parasites, dead host cells, and cellular and foreign debris by a cell. [22]
The mononuclear phagocyte system is part of both humoral and cell-mediated immunity. The mononuclear phagocyte system has an important role in defense against microorganisms, including mycobacteria, fungi, bacteria, protozoa, and viruses. Macrophages remove senescent erythrocytes, leukocytes, and megakaryocytes by phagocytosis and digestion.
Honoured as the "father of innate immunity", [16] [17] Metchnikoff was the first to discover a process of immunity called phagocytosis and the cell responsible for it, called phagocyte, specifically macrophage, in 1882.
The process of phagocytosis showing phagolysosome formation. Lysosome(shown in green) fuses with phagosome to form a phagolysosome. Membrane fusion of the phagosome and lysosome is regulated by the Rab5 protein, [1] a G protein that allows the exchange of material between these two organelles but prevents complete fusion of their membranes. [1]
Due to their role in phagocytosis, macrophages are involved in many diseases of the immune system. For example, they participate in the formation of granulomas, inflammatory lesions that may be caused by a large number of diseases. Some disorders, mostly rare, of ineffective phagocytosis and macrophage function have been described, for example ...
In anatomy the term reticuloendothelial system (abbreviated RES), often associated nowadays with the mononuclear phagocyte system (MPS), was employed by the beginning of the 20th century to denote a system of specialised cells that effectively clear colloidal vital stains (so called because they stain living cells) from the blood circulation.