TNFSF11 and rheumatoid arthritis: It is primarily secreted by macrophages and dendritic cells.14 It is highly expressed in serum, synovial tissue and synovial fluid of patients suffering from RA and has a positive association with disease activity.15 IL-18 accelerates the bone destruction in rheumatoid patients by indirectly stimulating the osteoclasts by up regulation of both soluble and membrane bound receptors i-e Receptor Activator of Nuclear Factor κB Ligand (RANKL) by RA synovial derived T cells.