The role of T cells in osteoporosis, an update.

Emerging evidence highlights the importance of the interplay between the bone and immune systems. That evidence bolsters a longstanding recognition that estrogen deficiency, infection, inflammation, and autoimmune disorders are associated with systemic and local bone loss. Yet, only recently has an understanding emerged that T lymphocytes and their products act as key regulators of osteoclast formation, life span, and activity. This review presents this understanding of the process of T lymphocytes and their products mediating osteoporosis and explores some of the most recent findings and hypotheses to explain their action in bone. A more complete appreciation of the interactions between immune and bone cells should lead to targeted therapeutic strategies for diseases that affect either or both systems.