Mast cells in the synovium and synovial fluid in osteoarthritis.

SF and synovium from normal individuals and patients with OA, RA and traumatic arthritis (TA) were studied for the presence of mast cells (MC). When compared with normals, patients with OA had large numbers of intact and degranulated MC in the synovium and SF of diseased joints. The numbers of MC are comparable with those in RA where they have been implicated in the pathogenesis of joint damage. These data raise the possibility that in OA too MC may participate in the pathological processes in articular and periarticular tissues.