mast cell
mast cell
mast cell
mast′ cell`
n.
Noun | 1. | mast cell - a large connective tissue cell that contains histamine and heparin and serotonin which are released in allergic reactions or in response to injury or inflammation |
单词 | mast cell | |||
释义 | mast cellmast cellmast cellmast′ cell`n.
Mast Cellmast cell[′mast ‚sel]Mast Cell(also called mastocyte or labrocyte), a reticular connective tissue cell in animals and man. The number of mast cells depends on the species and on the functional state of the connective tissue. The mast cell contains metachromatic cytoplasmic granules; the size and number of granules depend on the species and on the maturity and functional state of the cell. Mast cells contain a number of physiologically active substances, notably heparin, histamine, and serotonin. Consequently, it is believed that the mast cell plays a role in anaphylaxis, inflammation, and blood clotting. Mast cells rarely divide by mitosis. The principles of their origin and reproduction remain obscure. mast cellmast cellmast cellmast cellA ubiquitous immune surveillance cell, which is larger than basophils, with irregular and frequently elongated spindle shapes and cytoplasmic extensions. Mast cell (MC) nuclei are round and usually visible among the granules, which may overlay the edges of the nucleus slightly; the cytoplasm is usually packed with black or bluish-black metachromatic granules. MCs have a long—months to years—lifespan, in contrast to other “nonspecific” immune cells, such as PMNs (hours) or macrophages (weeks to months); they proliferate at the site of inflammation, have receptors for CR3 (complement), FcγR (IgG) and FcεR (IgE).Like basophils, MCs are activated by cross-linking of IgE on the cell surface and secrete neutrophil and eosinophil chemotactic factors, histamine, leukotrienes, neutral proteases, peroxidase, serotonin, superoxide dismutase, PGs and platelet-activating factor; factor release may be evoked by various substances (e.g., hormones, peptides, proteins, calcium ionophores, narcotics, muscle relaxants, dextran, complement C3a and C5a (anaphylotoxins)). The MC is detected by measuring serum trypticase, a neutral protease in MC secretory granules; levels > 4 ng/ml indicate systemic mast cell activation. Found in connective tissue, MCs secrete histamine and heparin, causing some of the changes of allergic reactions, phagocytoses and killing of bacteria. mast cell(mast sel)Synonym(s): mastocyte. mast cellmast cellA connective tissue cell found in large numbers in the skin and mucous membranes and in the lymphatic system. The mast cell plays a central part in allergic reactions. It contains numerous large granules-collections of powerfully irritating chemical substances such as HISTAMINE; SEROTONIN; HEPARIN; the proteases tryptase and chymase; CYTOKINES; PROSTAGLANDINS; and LEUKOTRIENES. In people with allergies, the antibody (immunoglobulin), IgE, remains attached to specific receptors on the surface of the mast cells. When the substance causing the allergy (the ALLERGEN) contacts the IgE, the mast cell is triggered to release these substances and the result is the range of allergic symptoms and signs. CHROMOGLYCATE can stabilize the mast cell membrane and prevent the release of the contents. Mast cells closely resemble blood basophil cells, and the latter also carry receptors for IgE. The mast cell has recently emerged as an important element in the inflammatory events leading to joint damage in RHEUMATOID ARTHRITIS. See also ATOPY.mast cella type of large, amoeboid cell found in the matrix of CONNECTIVE TISSUE, that produces HEPARIN and HISTAMINE and is probably important in quick-acting responses to ANTIGENS (see IMMUNE RESPONSE).Mast cellmast cell(mast sel)mast cell
Synonyms for mast cell
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