Chemokines and Chemokine Receptors

Chemokines (CKs) are a family of small proteins secreted by a great variety of cell types. Their name (derived from chemoattractant cytokines) is due to their ability to induce directed chemotaxis in nearby responsive cells. Some CKs are considered pro-inflammatory and can be induced during an immune response to promote cells of the immune system to a site of infection, whereas others are considered homeostatic and are involved in controlling the migration of cells during normal processes of tissue maintenance or development. CKs are found in all vertebrates, some viruses and some bacteria. These proteins exert their biological effects by interacting with G protein-linked transmembrane receptors called chemokine receptors (CKRs) that are selectively found on the surfaces of their target cells. CKs play roles in cell maturation and differentiation, infection, autoimmunity, cancer and, in general, in any situation where immune components are involved. Their role in human immunodeficiency virus (HIV) infection is of special relevance.