Recent data are presented illustrating a critical role of IL-18 in rheumatoid arthritis (RA). The T cells and macrophages invading the synovium or in synovial fluid are chief cellular targets of IL-18 in RA. Neutrophils, dendritic cells and endothelial cells may also be the cellular mediators of IL-18. The direct effect of IL-18 on fibroblast-like synoviocytes or chondrocytes may not be essential or important. In RA, IL-18, mainly produced by macrophages, activates T cells and macrophages to produce proinflammatory cytokines, chemokines, adhesion molecules and RANKL, which in turn perpetuates chronic inflammation, and induces bone and cartilage destruction.
- rheumatoid arthritis