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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.
Phagocytosis of an otherwise-viable cell may occur because the cell is recognised as stressed, activated, senescent, damaged, pathogenic or non-self, or is misrecognised. Cells are phagocytosed as a result of: i) expressing eat-me signals on their surface, ii) losing don’t-eat-me signals, and/or iii) binding of opsonins .
Phagocytosis, derived from the Greek words phagein, meaning to eat, kytos or cell, and “osis” meaning process, was first described by Élie Metchnikoff, who won the Nobel Prize 100 years ago. Phagocytosis involves the internalization of solids, such as bacteria, by an organism. Phagocytosis in Three Steps
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.
Phagolysosome resolution is the final stage in the phagocytic process, involving the breakdown of engulfed material and the recycling of phagolysosomal components. Most studies do not image the process of phagocytosis to completion, instead using lysosome fusion or acidification of the phagolysosome lumen as endpoints.
Thus, phagocytosis is not a randomly occurring event. It is triggered by a ligand binding to a receptor. Some cells are specially designed to phagocytize. These cells include Natural Killer cells, macrophages, and neutrophils. All of these are involved in the immune response and serve to degrade foreign or antigenic material [4]
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]
Phagocytosis is the process of uptake of microbes and particles followed by digestion and destruction of this material. Monocytes can perform phagocytosis using intermediary ( opsonising ) proteins such as antibodies or complement that coat the pathogen, as well as by binding to the microbe directly via pattern recognition receptors that ...