cytokine
Meaning of cytokine: Cytokines are small signaling proteins that immune cells release to coordinate inflammation and communication between cells during infection or injury.
Definition of cytokine
A cytokine is a small protein released mainly by cells of the immune system that acts as a chemical signal between cells. Once released, a cytokine binds to receptors on nearby or distant cells, triggering changes in their behavior, including growth, activation, or movement toward a site of infection or injury.
Different cytokines have different effects, and some promote inflammation and activate immune defenses, while others suppress immune activity and help bring a response back under control once a threat has passed. Interleukins, interferons, and tumor necrosis factor are among the many recognized types of cytokines.
Cytokines can also be produced in a laboratory using recombinant DNA technology and used as medications, including certain treatments for cancer and immune conditions, and abnormal or excessive cytokine activity is increasingly studied for its role in the tissue damage seen in some severe infections and inflammatory diseases.
Used in a sentence
Elevated cytokine levels were noted on laboratory testing during the acute phase of the infection.
Good to know
A single cytokine can have very different effects depending on which cell type it acts on and what other signals are present at the same time, so its effect cannot be predicted from its name alone.
Word origin
Where “cytokine” comes from
Formed from Greek kytos, meaning cell, and kinein, meaning to move, describing the molecule's role in prompting other cells into action.