Expression of CD69 antigen on synovial fluid T cells in patients with rheumatoid arthritis and other chronic synovitis

Increased expression of the CD69 antigen may occur on the surface of synovial fluid T cells in patients with rheumatoid arthritis (RA) and other types of chronic synovitis. Chronic synovitis is inflammation of the synovial membrane that lines the joint cavity. Synovial fluid is secreted by the synovial membrane to lubricate the joint. A study examined expression of the CD69 antigen on the surface of synovial fluid and peripheral blood T cells from 12 patients with RA and five patients with other types of chronic synovitis. Expression of the CD69 antigen was also examined in peripheral blood T cells from 15 patients with systemic lupus erythematosus and immune vasculitis. Increased expression of the CD69 antigen was found on the synovial fluid T cells from patients with RA or other types of chronic synovitis. Expression of the CD69 antigen was within a normal range on the peripheral blood T cells from all three patient groups.