cytokine
Americannoun
noun
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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.
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Also called chemokine
Usage
What is a cytokine? A cytokine is a type of protein released by cells in the body to carry messages to other cells. These messages tell the cells to do something, like to start an immune response. Cytokines get triggered by the presence of an antigen, which is any substance, such as a bacterium or virus, that causes the body to produce antibodies. There are many different types of cytokines. Common types are interleukins and lymphokines, which include the cytokines known as interferons. Cytokines play an important role in many different processes, including the regulation of inflammation and the immune response. Sometimes, though, too many cytokines get released. This is known as a cytokine storm, and it makes the body attack itself, resulting in potentially deadly damage to healthy tissue.
Etymology
Origin of cytokine
First recorded in 1970–75; cyto- ( def. ) + -kine, from Greek kineîn “to move, set in motion”; cf. -kinin ( def. )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
This leads to stronger internal signaling, which increases T-cell activation, boosts cytokine production, and improves the cells' ability to kill tumors.
From Science Daily • Apr. 10, 2026
"In addition, LC-Mo correlated with the severity of fatigue and respiratory symptoms and was associated with elevated cytokine levels in blood plasma, which are an indicator of inflammatory processes in the body."
From Science Daily • Mar. 26, 2026
Mice receiving arginine also performed better in behavioral assessments and showed decreased expression of pro-inflammatory cytokine genes linked to neuroinflammation, a key contributor to AD progression.
From Science Daily • Nov. 21, 2025
Conversely, when researchers injected the rats with a substance that agitates the immune system, the inflammatory cytokine levels rapidly shot up.
From Science Daily • Dec. 5, 2024
The study found that PM2.5 exposure can influence the histone profiles of pregnant women, disrupting the normal balance of cytokine genes and leading to increased inflammation in both women and fetuses.
From Science Daily • Nov. 29, 2024
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.