CCL21

CCL21, also known as C-C motif chemokine ligand 21, has alternative names including ECL, SLC, CKb9, TCA4, and SCYA21. CCL21 is a small molecule cytokine belonging to the CC chemokine family. It is primarily constitutively expressed at the origin of lymphatics and in lymphoid organs, present on several types of stromal cells and high endothelial villi (HEV). CCL21 can bind to glycosaminoglycans (GAGs) and fix itself to the surface of endothelial cells.
The biological functions of CCL21 are achieved through its binding to chemokine receptors CCR7 and CXCR3. CCL21 has chemotactic effects on thymocytes and activated T cells in vitro but does not chemotactically affect B cells, macrophages, or neutrophils. Additionally, CCL21 is an effective stimulator of T cell migration and adhesion, promoting the migration of T cells to secondary lymphoid organs and playing a crucial role in the homing of lymphocytes to secondary lymphoid organs, thus exerting significant immune regulatory functions.