[Study of C3 and C4 complement components of synovial fluids in connective tissue diseases (author's transl)]

C3 and C4 levels and the relative concentration of C3 degradation products were measured in fifty pairs of synovial fluids and sera of patients who suffered from different connective tissue diseases. Inverse correlation between C4 level and C3 breakdown products were found in synovial fluids of different groups. Compared to the other groups of patients, the highest increase of C3 degradation was found in RA. patients and it occurred in the SF all of these patients. In arthrosis cases we failed to find any degradation of C3. Of the seven investigated ankylosing spondylitis only two showed some degree of activation of C3 in the SF. Our results suggest that the occurrence and degree of degradation of C3 complement component is a valuable laboratory parameter in the study of connective tissue diseases.