CCl3

CCL3, also known as C-C motif chemokine ligand 3 and macrophage inflammatory protein 1-alpha (MIP-1α), is a chemokine in the CC chemokine family. In humans it is encoded by the CCL3 gene. CCL3 is a small secreted protein that functions primarily as a chemoattractant, directing immune cells to sites of infection or tissue injury.

Cells that produce CCL3 include macrophages, monocytes, dendritic cells, T lymphocytes, and various epithelial cells. Its expression is upregulated by pro-inflammatory stimuli such as lipopolysaccharide, interleukin-1, and tumor necrosis factor-α. CCL3 signals mainly through the receptors CCR1 and CCR5, inducing chemotaxis and activation of target cells and contributing to inflammatory amplification and host defense. Through its interaction with CCR5, CCL3 can influence HIV-1 infection dynamics by competing with the virus for coreceptor binding.

Genetics and related genes: CCL3 is located in a cluster of CC chemokine genes on chromosome 17. It is closely related to CCL4 (macrophage inflammatory protein 1-beta) and to paralogous genes such as CCL3L1, which exhibits copy-number variation in the human genome. Variation in CCL3 and its related genes has been studied for potential roles in susceptibility to infections and in shaping the inflammatory response.

Clinical relevance: Elevated CCL3 levels are observed in various inflammatory and autoimmune conditions, including rheumatoid arthritis and inflammatory bowel diseases, and it participates in the recruitment of immune cells during infection. Its interaction with CCR5 links it to discussions of HIV pathogenesis and host resistance, illustrating the broader role of CCL3 in immune regulation.