Synovial fluid and blood monocyte influence on lymphocyte proliferation in rheumatoid arthritis and traumatic...

The influence of synovial fluid and blood monocytes on autologous lymphocyte proliferation in vitro was investigated in patients with rheumatoid arthritis (RA) and traumatic synovitis (TS). In cultures stimulated with PHA, PWM and ConA, thymidine incorporation by RA blood mononuclear cells (BMC) increased considerably in most cases after addition of 10% or 30% synovial fluid monocytes and a similar effect was seen after stimulation with Candida extract or PPD. A comparable helper activity was observed after addition of synovial fluid monocytes to monocyte-depleted blood cells in RA. The augmenting effect of synovial fluid monocytes was likewise demonstrated in TS patients. Synovial fluid mononuclear cells (SMC) from RA and TS patients displayed low proliferative responses to PHA and ConA in comparison with BMC, while the responses to microbial antigens were similar or greater. The proliferative activity of SMC or of monocyte-depleted synovial fluid cells after polyclonal and antigenic stimulation was not affected by addition of blood monocytes. This was observed in both RA and TS patients. It is concluded that the regulatory properties of synovial fluid monocytes in RA and TS do not explain the low proliferative responses of SMC to polyclonal activators.