CD69 is an immunoregulatory molecule induced following activation

CD69 is an early leukocyte activation molecule expressed at sites of chronic inflammation. The precise role of CD69 in immunity has not been elucidated owing to the absence of a known ligand and adequate in vivo models to study its physiological function. Although previous in vitro studies suggest that CD69 is an activatory molecule in different leukocyte subsets, recent studies in CD69-deficient mice have revealed a non-redundant role for this receptor in downregulation of the immune response through the production of the pleiotropic cytokine transforming growth factor-β (TGF-β). The possible cellular and molecular mechanisms of action of this molecule are discussed herein. CD69 is an early leukocyte activation molecule expressed at sites of chronic inflammation. The precise role of CD69 in immunity has not been elucidated owing to the absence of a known ligand and adequate in vivo models to study its physiological function. Although previous in vitro studies suggest that CD69 is an activatory molecule in different leukocyte subsets, recent studies in CD69-deficient mice have revealed a non-redundant role for this receptor in downregulation of the immune response through the production of the pleiotropic cytokine transforming growth factor-β (TGF-β). The possible cellular and molecular mechanisms of action of this molecule are discussed herein.