CCL21

CCL21, also known as exodus-2 and secondary lymphoid chemokine (SLC), is a small cytokine belonging to the CC chemokine family and is located on chromosome 9 in the human genome. It binds to glycosaminoglycan (GAG) and is anchored to the surface of endothelial cells. As a chemokine, CCL21 inhibits hematopoiesis and stimulates chemotaxis, and is chemotactic in vitro for thymocytes and activated T cells, but not for B cells, macrophages or neutrophils. At the same time, CCL21 is a potent stimulator of T cell migration and adhesion, binding to the glycoprotein PSGL-1 on T cells to promote the migration of T cells to secondary lymphoid organs. CCL21 can act through chemokine receptors CCR7 and CXCR3. Among them, CCR7 is a GPCR that is normally expressed by T cell subsets central memory cells, thymic T cells, B cells, mature DCs and other rare cell subsets. ccl21 can function as a microglia activator in the CNS and is expressed exclusively in endangered or mechanically damaged neurons[1][2].