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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.
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]
Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of ...
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 process of phagocytosis is accompanied by virus degradation, but if the virus is not neutralized (either due to low-affinity binding or targeting to a non-neutralizing epitope), antibody binding may result in virus escape and, therefore, more severe infection. Thus, phagocytosis can cause viral replication and the subsequent death of immune ...
Opsonins induce phagocytosis of targets by binding the targets (e.g. bacteria) and then also binding phagocytic receptors on phagocytes. Thus, opsonins act as bridging molecules between the target and the phagocyte, bringing them into contact, and then usually activating the phagocytic receptor to induce engulfment of the target by the phagocyte.
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.
The process is tightly regulated and the inflammatory response varies depending on the particle type within the phagosome. Pathogen-infected apoptotic cells will trigger inflammation, but damaged cells that are degraded as part of the normal tissue turnover do not. The response also differs according to the opsonin-mediated phagocytosis.