Cytokines and chemokines are signaling molecules that play important roles in the immune system. They are secreted by immune cells and other cell types, and act on target cells to regulate immune responses.
Cytokines are a diverse group of proteins that include interleukins, interferons, tumor necrosis factors, and others. They are produced by a variety of immune cells, including T cells, B cells, macrophages, and dendritic cells, as well as by non-immune cells such as epithelial cells and fibroblasts. Cytokines can act on the same cell that produced them (autocrine), on neighboring cells (paracrine), or on distant cells (endocrine), and can have a wide range of effects on cell growth, differentiation, and function. For example, cytokines can promote cell proliferation, differentiation, migration, activation, and apoptosis.
Chemokines are a type of cytokine that specifically regulate the migration and localization of immune cells. They are produced by a variety of cell types, including immune cells, endothelial cells, and epithelial cells. Chemokines act by binding to chemokine receptors on the surface of immune cells, which triggers intracellular signaling pathways that control cell migration and adhesion. Chemokines are critical for immune cell recruitment to sites of infection or inflammation, and defects in chemokine signaling can lead to immune dysfunction and disease.
Both cytokines and chemokines are involved in the regulation of immune responses, including inflammation, host defense against pathogens, and the development of immune tolerance. Dysregulation of cytokine and chemokine signaling can lead to immune dysfunction and disease, such as autoimmunity, allergy, and immunodeficiency. Therefore, cytokines and chemokines are important targets for the development of immunomodulatory drugs for the treatment of various immune-related disorders.