Markers of collagen metabolism in sera of patients with various rheumatic diseases.

The activity of galactosylhydroxylysyl glucosyltransferase (S-GGT) and concentration of the amino-terminal propeptide of type III procollagen, measured with two different radioimmunoassays, S-Pro(III)-N-P and S-Fab, were determined in the sera of 209 patients with various rheumatic diseases. The mean values for all these three assays were elevated in the patients with rheumatoid arthritis, whereas only the mean value for S-GGT was elevated in osteoarthrosis. The mean S-GGT but not S-Pro(III)-N-P or S-Fab was also elevated in psoriatic arthritis, ankylosing spondylitis and systemic lupus erythematosus. S-GGT correlated significantly both with S-Pro(III)-N-P and S-Fab in the pooled group of all the patients and in the cases of rheumatoid arthritis and psoriatic arthritis, and also with S-Fab in the cases of osteoarthrosis. S-Pro(III)-N-P and S-Fab correlated with each other in every disease group. The ratio S-Fab:S-Pro(III)-N-P was significantly higher in the patients with osteoarthrosis, ankylosing spondylitis and systemic lupus erythematosus than in those with rheumatoid arthritis. The data indicate that definite changes can be seen in the values of serum markers of collagen metabolism in rheumatoid arthritis, psoriatic arthritis, osteoarthrosis, ankylosing spondylitis and systemic lupus erythematosus, the most sensitive indicator being S-GGT.