T cells in psoriatic arthritis.

Psoriatic arthritis is characterized by chronic inflammation of the skin and synovial joint. T cells are abundant in the inflamed joint and skin. Disease susceptibility is associated with major histocompatibility complex, which presents antigens to T cells. T cells in the synovial joints have an activated phenotype and demonstrate selective T-cell receptor usage suggestive of oligoclonal expansions. Taken together, these facts suggest that psoriatic arthritis is driven by antigen or autoantigen-driven T-cell activation. The therapeutic benefit of anti-T-cell agents further supports an important pathogenic role for T cells in persistent synovial inflammation and joint damage in psoriatic arthritis.