T Cells and TNF (Tumor Necrosis Factor): The Impact of TNF Blockade

Inflammatory arthritis particularly rheumatoid arthritis (RA), psoriatic arthritis and ankylosing spondylitis are potentially disabling conditions which cause joint pain, swelling and deformity and treatments are aimed at preventing these complications. Although treatment has improved with the advent of anti TNF alpha therapies, up to 30% of patients fail to respond to this treatment and in others, treatment is associated with significant side effects. The precise mechanisms of this remain unclear. In addition, there are no sensitive methods available to monitor or predict disease response to treatment aside from testing inflammatory markers in the blood. Understanding the mechanism of action and what governs response to anti TNF therapy will allow development of more specific therapies for inflammatory arthritis. Work in animal models of rheumatoid arthritis has characterised a novel cell type, Th17 cells, important in the inflammatory cascade which are affected in a particular way by anti TNF therapies and may underpin their mechanism of action and side effects.