Receptor activator of NF-κB ligand enhances the activity of macrophages as antigen presenting cells

Receptor activator of NF kappa B ligand (RANKL) is known as a key regulator of osteoclastogenesis. However, the fact that fibroblasts and periodontal ligament cells express RANKL in response to bacterial sub stances, suggests that RANKL may have evolved as a part of the immunity to infection. As RANKL increases the survival and activity of dendritic cells, it may have similar effects on macrophages. To address this issue, we studied the effect of RANKL on various functions of macrophages using mouse bone marrow derived macrophages. RANKL enhanced the survival of macrophages and up-regulated the expression of CD86. RANKL-treated macro phages showed increased allogeneic T cell activation and phagocytic activity compared to control cells. In addition, RANKL increased the expression of TNF alpha, MCP-1, and IL-6 but not of IL-10, IL-12, IFN-gamma, and iNOS. Collectively, RANKL augmented the activity of macrophages especially as antigen presenting cells, suggesting its new role in immune regulation.