| [ Summary ] |
Although activated T cells were thought to enhance osteoclast differentiation via RANKL expression on their surface, both Th1 and Th2 cells strongly suppressed osteoclastogenesis through the effects of IFN-γ and IL-4, respectively. In the process of seeking Th subsets that can enhance osteoclastogenesis, we discovered a new subset that could be differentiated in the presence of IL-23, anti-IFN-γ Ab and anti-IL-4 Ab. These cells are now called Th17 cells. They produce a great deal of IL-17 but little IFN-γ or IL-4. Th17 cells did enhance osteoclastogenesis, mainly through inducing RANKL on osteoclast-supporting cells such as osteoblasts. They may play an important role in the pathogenesis of rheumatoid arthritis and provide novel information related to basic research and clinical immunology. |