The comunication between skeletal and immune systems is formed by interaction of skeletal and immune cells. The receptor activator of nuclear factor-κB ligand plays an important role in the development of bone and immune organs, as well as in autoimmune arthritis. Here we briefly introduce the structures and biological functions of the skeletal and immune systems, and
describe the interactions between them with emphasis on the osteoprotegerin/receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factor-κB(OPG/RANKL/RANK), which functions as a linkage between the skeletal and the immune systems.