[Elevated C3-proactivator serum levels in patients with chronic polyarthritis].

The C3-Proactivator (C3-PA) and the C3 and C4 complements were determined by radio-immuno diffusion in the serum of 72 patients with definite or classical rheumatoid arthritis, 51 patients with osteoarthrosis and 42 healthy subjects. C3-PA and C4 levles were significantly higher in the serum of patients with rheumatoid arthritis than in the control group (C3-PA in 72%, C4 in 37% of the RA patients). There was also a significant difference between seropositive und seronegative cases. Elevation of both components was more frequently found in patients with seronegative rheumatoid arthritis than in the seropositive cases. However, the C3-PA serum level is not correlated with the ESR. Also an elevation of the C3-PA serum level is not specific for rheumatoid arthritis, it is also found in other inflammatory diseases as well as after surgery.