Cytokines: Role in Homeostasis and Disease States
Cytokines are a group of short proteins secreted by cells as a means of intercellular communication. They play an essential role in numerous physiological processes including, but not limited to, immune regulation and inflammatory responses through autocrine, paracrine, or endocrine mechanisms. Cytokines elicit a variety of responses such as cell activation, proliferation, differentiation, angiogenesis, hematopoiesis, and inflammation. Every cell in the body, with the exception of red blood cells, can produce and respond to a cytokine. Thus, they are frequently measured to assess the potential impact, either desired or undesired, of a xenobiotic or therapeutic agent on immune function. This chapter briefly discusses the various cytokine families and their major functions, describes some of the current technologies used to measure cytokines, examines the role of cytokines in normal homeostasis and physiology, and touches upon translational challenges in differentiating pharmacodynamic effects from exaggerated pharmacology (i.e. toxicity) when immune modulation is the desired outcome.