phagocytosis


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phagocytosis:

see endocytosisendocytosis
, in biology, process by which substances are taken into the cell. When the cell membrane comes into contact with a suitable food, a portion of the cell cytoplasm surges forward to meet and surround the material and a depression forms within the cell wall.
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Phagocytosis

A mechanism by which single cells of the animal kingdom, such as smaller protozoa, engulf and carry particles into the cytoplasm. It differs from endocytosis primarily in the size of the particle rather than in the mechanism; as particles approach the dimensions and solubility of macromolecules, cells take them up by the process of endocytosis.

Cells such as the free-living amebas or the wandering cells of the metazoa often can “sense” the direction of a potential food source and move toward it (chemotaxis). If, when the cell contacts the particle, the particle has the appropriate chemical composition, or surface charge, it adheres to the cell. The cell responds by forming a hollow, conelike cytoplasmic process around the particle, eventually surrounding it completely. Although the particle is internalized by this sequence of events, it is still enclosed in a portion of the cell's surface membrane and thus isolated from the cell's cytoplasm. The combined particle and membrane package is referred to as a food or phagocytic vacuole. See Vacuole

Ameboid cells of the metazoa also selectively remove foreign particles, bacteria, and other pathogens by phagocytosis. After the foreign particle or microorganism is trapped in a vacuole inside the macrophage, it is usually digested. To accomplish this, small packets (lysosomes) of lytic proenzymes are introduced into the phagocytic vacuole, where the enzymes are then dissolved and activated. See Lysosome

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Phagocytosis

 

the engulfing and absorption of living and nonliving particles by unicellular organisms or specialized cells—phagocytes—in multicellular animals. Phagocytosis was discovered by E. Metchnikoff (I. I. Mechnikov), who traced its evolution and elucidated its function in the defense reactions of the higher animals and man, particularly those related to inflammation and immunity. The process plays a major role in the healing of wounds.

The ability to seize and digest particles, which is the basis of nutrition in primitive organisms, was gradually transferred in the course of evolution to certain specialized cells—initially to the digestive cells and later to some special cells in the connective tissues. In mammals and in man, the neutrophils (that is, micro-phages, or specialized leukocytes) and the reticuloendothelial cells are active phagocytes capable of being transformed into active macrophages. The neutrophils phagocytize small particles, such as bacteria, while macrophages can ingest such larger particles as dead cells and their nuclei and fragments. Marcrophages can also store the negatively charged particles of pigments and of colloidal substances. The ingestion of small colloidal particles is called ultraphagocytosis.

Phagocytosis—a process that requires the expenditure of energy—involves primarily the activity of the cell membrane and intracellular organoids, or lysosomes, which have a high content of hydrolytic enzymes. Phagocytosis proceeds in stages. After a phagocytable particle has attached itself to the cell membrane, an intracellular corpuscle, or phagosome, is formed by invagination of the membrane and the particle. Hydrolytic enzymes enter the phagosome from the surrounding lysosomes and digest the phagocytized particle. Depending on the particle’s physiochemi-cal properties, digestion may be complete or incomplete. In the latter case, a residual corpuscle is formed and may remain in the cell a long time.

REFERENCES

Mechnikov, I. I. Izbrannye biologicheskie proizvedeniia. Moscow, 1950.
Zil’ber, L. A. Osnovy immunologii, 3rd ed. Moscow, 1958.

N. G. KHRUSHCHOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

phagocytosis

[‚fag·ə‚sī′tō·səs]
(cell and molecular biology)
A specialized form of macropinocytosis in which cells engulf large solid objects such as bacteria and deliver the internalized objects to special digesting vacuoles; exists in certain cell types, such as macrophages and neutrophils.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The murine macrophage cell line, RAW264.7 was used as an in vitro model to investigate cigarette smoke exposure and its impact on phagocytosis. Standard cell culture procedures as previously described were used [14].
Considering that TAMs contribute to the formation of an immunosuppressed state within the TME, one of the therapeutic strategies targeting TAMs is reeducating TAMs to an antitumor phenotype, such as promoting macrophages' phagocytosis ability [18, 19].
Excessive expression of MMPs is associated with the pathology of many diseases.[sup][4],[5] In addition to their ability to facilitate migration, there is abundant evidence that MMPs are involved in immunological processes, such as endocytosis, major histocompatibility complex (MHC)-I presentation, and cytokine/chemokine release.[sup][4],[5],[6],[7],[8] MMP-13 is an ECM-degrading endopeptidase and is primarily expressed in chondrocytes and osteoblasts, and functions in bone metabolism and homeostasis.[sup][9],[10] Studies of MMP-13 revealed that it is also expressed in murine bone marrow-derived DCs, but to our knowledge, very few reports have ever been published regarding the function of MMP-13 in DCs, particularly regarding its role in DC maturation, apoptosis, and phagocytosis.
In the macrophage, triggering of phagocytosis of a target cell is based on the balance between positive prophagocytic signals and inhibitory CD47/SIRP[alpha] signaling.
Interferon-a/dexamethasone affected the dendritic cells capacity in stimulating T cells proliferation and phagocytosis
Just a handful of genes were involved in both phagocytosis and inflammation.
The effect of PLGA-PEG amount to phagocytosis hindrance was evaluated by varying the PLGA to PLGA-PEG mass ratio in the initial formulation to 1 : 0 (NC0%), 9 : 1 (NC10%), 4: 1 (NC20%), 3 : 2 (NC40%), 2 : 3 (NC60%), and 1: 4 (NC80%) while keeping the total polymer amount constant (100 mg).
Phagocytosis is a specific type of behavior for M2 macrophages and other phagocytes.
Many studies have shown the benefits of these lipid mediators that can limit tissue infiltration of polymorphonuclear leukocytes (PMNs), reduce collateral tissue damage by phagocytes, shorten the resolution interval (Ri), enhance macrophage phagocytosis and efferocytosis, and counterregulate proinflammatory chemical mediators [9].
Instead, density-gradient centrifugation splits them into distinct subpopulations with differences in the expression of surface markers and intracellular enzymes as well as tumour lysis, migration, cytotoxicity, phagocytosis, lymphoproliferative response augmentation, soluble mediator release, and procoagulant activity [33-42].
SRBCs were washed three times with PBS.In vitro phagocytosis of SRBCs was performed in colchicine treated groups, negative and positive control groups by macrophages (Javeed et al., 2011; Loike et al.,2004; Seyrantepe et al.,2010).