The T cell receptor repertoire in psoriatic synovitis is restricted and T lymphocytes expressing the same TCR are present in joint and skin lesions.

OBJECTIVE: To investigate the T cell receptor (TCR) repertoire in psoriatic synovitis and to determine whether T lymphocytes in joint and skin lesions show the same Vbeta CDR3 region. METHODS: The expression of Valpha and Vbeta families was evaluated by reverse transcriptase-polymerase chain reaction. The CDR3 region of some Vbeta families was analyzed by cloning and sequencing. RESULTS: We found a diverse variable beta chain usage within psoriatic synovial fluid of 11 patients although some Valpha and Vbeta families were more frequently expressed without evidence of clonality. Analysis of TCR in skin and synovial lesions of 3 patients showed identical CDR3 sequences, indicating that T cells bearing the same TCR are present at the 2 sites of chronic inflammation. CONCLUSION: These data suggest that common or similar crossreactive antigens present in the 2 locations are responsible for the expansion of the same TCR-bearing T cells possibly already activated by a superantigen. This supports the hypothesis that both polyclonal and oligoclonal lymphocyte activation contribute to the initiation and persistence of psoriatic arthritis.