Selective expansion of t cells bearing the γ/δ receptor and expressing an unusual repertoire in the synovial membrane of patients with rheumatoid arthritis

Abstract

In a study of 7 patients with rheumatoid arthritis (RA), we characterized the T cell population present in the synovial membrane, thought to be the location where T cells trigger the disease. Synovial membrane lymphocytes from the RA patients were found to have a selective expansion of γ/δ T cells (8.8% in synovial membrane versus 4% in peripheral blood). Expansion of the γ/δ T cell subset was not found in the synovial membrane of patients with osteoarthritis. We characterized the γ/δ T cell repertoire using monoclonal antibodies TiγA, BB3, and δTCS1, which recognize the gene products encoded by V_γ9, V_δ2, and V_δ1‐J_δ1, respectively. The majority of the synovial γ/δ T cells did not express the repertoire encoded by these genes, which is found in nearly 100% of the peripheral blood γ/δ T cells of healthy volunteer donors and in the thymus at early stages of development. We conclude that the synovial membrane of patients with RA displays a selective expansion of a specific population of γ/δ T cells expressing a clonotypic receptor not yet serologically defined, which might be implicated in the development of the disease.