What are cytokines? A collection of polypeptides used for communications between cells Play role similar to hormones(messengers of the endocrine system) Hormones usually act at a distance Cytokines act locally Differ from growth factors that are produced constitutively,while cytokine production is carefully regulated Play an important role in both innate and adaptive immunity What are cytokines? ◼ A collection of polypeptides used for communications between cells ◼ Play role similar to hormones (messengers of the endocrine system) ◼ Hormones usually act at a distance ◼ Cytokines act locally ◼ Differ from growth factors that are produced constitutively, while cytokine production is carefully regulated ◼ Play an important role in both innate and adaptive immunity