SELECTIVE EXPANSION OF T-CELLS BEARING THE GAMMA-DELTA RECEPTOR AND EXPRESSING AN UNUSUAL REPERTOIRE IN THE SYNOVIAL-MEMBRANE OF PATIENTS WITH RHEUMATOID-ARTHRITIS

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 cell trigger the disease. Synovial membrane lymphocytes from the RA patients were found to have a selective expansion of gamma/delta-T cells (8.8% in synovial membrane versus 4% in peripheral blood). Expansion of the gamma/delta-T cell subset was not found in the synovial membrane of patients with osteoarthritis. We characterized the gamma/delta-T cell repertoire using monoclonal antibodies Ti-gamma-A, BB3, and delta-TCS1, which recognize the gene products encoded by V-gamma-9, V-delta-2, and V-delta-1-J-delta-1, respectively. The majority of the synovial gamma/delta-T cells did not express the repertoire encoded by these genes, which is found in nearly 100% of the peripheral blood gamma/delta-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 gamma/delta-T cells expressing a clonotypic receptor not yet serologically defined, which might be implicated in the development of the disease.