Induction of peripheral blood lymphocyte transformation by autologous synovial fluid lymphocytes and synovial fluid.

Synovial fluid lymphocytes and synovial fluid from most patients with rheumatoid arthritis induced blastogenesis of autologous peripheral blood lymphocytes. In vitro transfer of the mitogenic activity of the synovial fluid to peripheral blood lymphocytes was not accomplished, but diminished response of the peripheral blood lymphocytes to phytohemagglutinin stimulation after incubation in synovial fluid was demonstrated. These findings suggest that a similar blastogenic response in vivo may induce the lymphoid hyperplasia regularly observed in rheumatoid arthritis.