Chemokines
Chemokines are a family of secreted cytokine proteins characterized by their small size and ability to act as chemoattractants to guide the migration of nearby responsive cells. Pro-inflammatory chemokines are induced during an immune response to sites of bacterial infection and tissue damage. Other chemokines are considered homeostatic and involved in controlling the migration of cells during normal processes of tissue maintenance and development, such as the growth of new blood vessels. Pro-inflammatory chemokines, such as the interleukins (IL-1, IL-6, IL-8, etc.) function mainly as attractants of leukocytes, recruiting monocytes, neutrophils and other effector cells from the blood to sites of infection or damage in response to both innate and adaptive immune system triggers. Chemokines exert their biological effects by interacting with transmembrane G protein-coupled receptors (GPCRs) that are found on the surface of target cells.