[CH50, C3 and C4 in the serum and synovial fluid of rheumatoid arthritis patients].

The total hemolytic complement (CH50) was studied in the serum of 54 patients suffering from rheumatoid arthritis (RA) and in the synovia of 30 of them. The C3 complement fraction was examined in the serum of 49 patients and in the synovia of 30 patients. The C4 complement serum-fraction was examined in 42 patients and in the synovia of 30 patients. 40 healthy persons and 21 patients with osteoarthritis served as a control group. The results showed a slight increase of CH50 in the serum and decrease in the synovia of the patients with RA compared to the control groups. The serum values of C3 and C4 of the RA patients did no differ from those of the healthy persons but the synovial C3 and C4 values were lowered. A reverse correlation was found between the CH50 in the synovial fluid and the phagocyte percentage in the fluid (r = -0.43). CH50, C3 and C4 determination is important for clarification of some pathogenetic mechanisms in RA. Their decrease reflects the degree of immunologic activity.