What is the definition of a cytokine?

A cytokine is defined as a signaling peptide that plays a crucial role in the immune response and cell communication. These small proteins are released by cells and act as messengers to facilitate communication between immune cells and other types of cells in the body. Cytokines can influence the behavior of other cells by binding to specific receptors on their surfaces, initiating a variety of immune responses such as inflammation, cell proliferation, and differentiation.

In the context of the immune system, cytokines include a wide range of molecules such as interleukins, interferons, and tumor necrosis factors. Their functions are diverse, helping to coordinate the activities of immune cells and facilitate communication during both innate and adaptive immune responses. By directing cell movements, activating pathogen-fighting mechanisms, and modulating the balance between tolerance and immunity, cytokines are essential for maintaining homeostasis and responding to infections or injuries.

Understanding cytokines is vital as they play a significant role in various diseases and conditions, including autoimmune disorders, infections, and cancer. Therapies that target cytokine signaling pathways are important in treating these conditions, further highlighting the significance of these signaling peptides in health and disease.