cytokine [sīt′ō kīn΄]
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 (sīʹtə-kīn') n.
Any of several regulatory proteins, such as the interleukins and lymphokines, that are released by cells of the immune system and act as intercellular mediators in the generation of an immune response.
  [cyto- + Greek kīnein, to move; see kinin.]

* * *

      any of a group of small, short-lived proteins that are released by one cell to regulate the function of another cell, thereby serving as intercellular chemical messengers. Cytokines effect changes in cellular behaviour that are important in a number of physiological processes, including reproduction, growth and development, and injury repair. However, they are probably best known for the roles they play in the immune system's defense against disease-causing organisms.

      As part of the immune response, cytokines exert their influence over various white blood cells (leukocytes (leukocyte)), including lymphocytes, granulocytes, monocytes, and macrophages. Cytokines produced by leukocytes are sometimes called interleukins, while those produced by lymphocytes may be referred to as lymphokines.

      Cytokines typically are not stored within the cell but instead are synthesized “on demand,” often in response to another cytokine. Once secreted, the cytokine binds to a specific protein molecule, called a receptor, on the surface of the target cell, an event that triggers a signaling cascade inside that cell. The signal ultimately reaches the nucleus, where the effects of the cytokine are manifested in changes in gene transcription and protein expression—i.e., genes, which code for proteins, may be turned on or off, and protein production may be stimulated or inhibited.

      Many different cytokines have been identified, and their activities, at least in part, are known. In some cases, one cytokine can interact with a variety of different cell types and elicit different responses from each cell. In other cases, different cytokines can elicit the same response from a cell. Some cytokines are known to induce or augment the activities of other cytokines, and sometimes their interactions occur through a cascading effect; however, the regulation of and cooperation between these various chemical signals still remain unclear in many cases. The classification of cytokines is problematic because so much remains to be learned about them, but they can be divided into five categories: interleukins (interleukin), interferons (interferon), colony-stimulating factors, tumour necrosis factors (tumour necrosis factor), and growth factors.

      Because cytokines are known to play a role in many disease processes, they have the potential to be used in treating a variety of disorders. For example, clinicians monitor levels of cytokines in the blood to assess the progression and activity of certain inflammatory states, such as septic shock. Measuring cytokine production also is useful in determining an individual's immunocompetence, or ability to fight off infection. Cytokines are used as therapeutic agents in treating persons with cancer and immunodeficiency disorders and those undergoing organ transplantation. Cytokines in conjunction with certain vaccines (vaccine) can enhance the vaccines' effectiveness.

* * *

Universalium. 2010.

Look at other dictionaries:

  • 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

  • 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… …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.