Cytokine


Cytokine
A small protein released by cells that has a specific effect on the interactions between cells, on communications between cells or on the behavior of cells. The cytokines includes the interleukins, lymphokines and cell signal molecules, such as tumor necrosis factor and the interferons, which trigger inflammation and respond to infections.
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Any of numerous hormonelike, low-molecular-weight proteins, secreted by various cell types, that regulate the intensity and duration of immune response and mediate cell-cell communication. See interferon, interleukin, lymphokine, chemokines. See entries under various growth factors. SEE ALSO: interferon, interleukin, lymphokine. [cyto- + G. kinesis, movement] Cytokines are produced by macrophages, B and T lymphocytes, mast cells, endothelial cells, fibroblasts, and stromal cells of the spleen, thymus, and bone marrow. They are involved in mediating immunity and allergy and in regulating the maturation, growth, and responsiveness of particular cell populations, sometimes including the cells that produce them (autocrine activity). A given c. may be produced by more than one type of cell. Some cytokines enhance or inhibit the action of other cytokines. The first cytokines to be identified were named according to their functions (e.g., T cell growth factor), but this nomenclature became awkward because several cytokines can have the same function, and the function of a c. can vary with the circumstances of its elaboration. Later, as the chemical structure of each c. was determined, it was designated an interleukin and assigned a number (e.g., interleukin-2 [IL-2], formerly T cell growth factor). Cytokines have been implicated in the generation and recall of long-term memory and the focusing of attention. Some of the degenerative effects of aging may be due to a progressive loss of regulatory capacity by cytokines. Because cytokines derived from the immune system (immunokines) are cytotoxic, they have been used against certain types of cancer.
- c. network a group of cytokines which together modulate and regulate key cellular functions.

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cy·to·kine 'sīt-ə-.kīn n any of a class of immunoregulatory proteins (as interleukin, tumor necrosis factor, and interferon) that are secreted by cells esp. of the immune system

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cy·to·kine (siґto-kīn) [cyto- + kinesis] a generic term for nonantibody proteins released by one cell population (e.g., primed T lymphocytes) on contact with specific antigen, which act as intercellular mediators, as in the generation of an immune response. Examples include lymphokines and monokines.

Medical dictionary. 2011.

Look at other dictionaries:

  • cytokine — [sīt′ō kīn΄] n. any of a group of molecules, including interferon, interleukin, and tumor necrosis factor, secreted by certain cells of the immune system which modulate certain cell functions associated with immune response * * * cy·to·kine… …   Universalium

  • cytokine — ● cytokine nom féminin Substance peptidique ou protéique (interféron, interleukine, lymphokine, etc.) synthétisée par une cellule du système immunitaire (lymphocyte, macrophage) et agissant sur d autres cellules immunitaires pour en réguler l… …   Encyclopédie Universelle

  • cytokine — [sīt′ō kīn΄] n. any of a group of molecules, including interferon, interleukin, and tumor necrosis factor, secreted by certain cells of the immune system which modulate certain cell functions associated with immune response …   English World dictionary

  • Cytokine — Cytokines (Greek cyto , cell; and kinos, movement) are small cell signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used… …   Wikipedia

  • Cytokine — Les cytokines (du grec cyto, cellule et kinos, mouvement) sont des substances solubles de communication synthétisées par les cellules du système immunitaire (les lymphocytes T) ou par d autres cellules et/ou tissus, agissant à distance sur d… …   Wikipédia en Français

  • cytokine — noun Etymology: cyt + kine (as in lymphokine) Date: 1979 any of a class of immunoregulatory proteins (as interleukin or interferon) that are secreted by cells especially of the immune system …   New Collegiate Dictionary

  • Cytokine — Ein Zytokin (auch: Cytokin) ist ein zuckerhaltiges Protein, das regulierende Funktionen für das Wachstum und die Differenzierung von Körperzellen ausübt. Es handelt sich um eine Gruppe von Peptiden, die vor allem die Proliferation und… …   Deutsch Wikipedia

  • cytokine — (si to kaīn) A general term for nonantibody proteins, released by a cell in response to inducing stimuli, which are mediators that influence other cells. Are produced by lymphocytes, monocytes, macrophages, and other cells …   Dictionary of microbiology

  • cytokine(s) — Small proteins (in the range of 5 20 kD) released by cells and that affect the behaviour of other cells. Not really different from hormones, but the term tends to be used as a convenient generic shorthand for interleukins, lymphokines and several …   Dictionary of molecular biology

  • cytokine — noun Any of various small regulatory proteins that regulate the cells of the immune system …   Wiktionary


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