Immune cells and bone: coupling goes both ways

There is a mounting body of research describing how cells of the immune system direct bone cell function whilst bone cells are involved in the generation and retention of immune cells and their precursors. Recent works into regulation of the haemopoietic stem cell niche have firmly implicated osteoblasts and osteoclasts. On the other hand, virtually all of the mature immune cells have been described to influence bone formation in vitro and in vivo. This review will summarize the latest developments and discuss the importance of the coupling of bone formation to resorption when considering the contributions from cells of the immune system.