A large family of cytokines are produced by various cells of the body, and the cytokine superfamily includes interleukins, chemokines, colony-stimulating factors (CSF), interferons, and the transforming growth factors (TNF) and tumor necrosis factor (TGF) familes. Cytokines exist in broad families that are structurally related but may contain rather diverse cytokine functions. Learn More.
Cytokines are a category of signaling molecules that mediate and regulate immunity, inflammation, hematopoiesis, and many other cellular processes, forming a cytokine network. Cytokines were initially identified as products of immune cells that act as mediators and regulators of immune processes but many cytokines are now known to be produced by cells other than immune cells and they can have effects on non-immune cells as well. Cytokines can also be secreted by glial cells of the nervous system. Cytokine is a general name; other names are defined based on their presumed function, cell of secretion, or target of action. For example, cytokines made by lymphocytes can also be referred to as lymphokines, while interleukins are made by one leukocyte and act on other leukocytes. And chemokines are cytokines with chemotactic activities. Cytokines may act on the cells that secrete them (autocrine action), on nearby cells (paracrine action), or in some instances on distant cells (endocrine action). Learn More.
Cytokine receptors contain one to three chains, one or more of which generally have limited similarity in the membrane-proximal region (often referred to as box1/box2 motifs). According to the nomenclature the ligand-binding subunit of a receptor is referred to as the alpha chain. Other signal transducing subunits are named beta chains, or gamma chains. All cytokine receptors are associated with one or more members of JAKs, which couple ligand binding to tyrosine phosphorylation of various signaling proteins (STATs) recruited to the receptor complex. Learn More.