Serum type I and type III procollagen peptide levels in sarcoidosis

Type I and type III are the most abundant collagens in the lung, The aim of our study was to compare type I and III procollagen peptides in sera of sarcoid patients. Sixty eight patients with sarcoidosis were studied (19 with newly recognized disease, 7 with relapsing disease, 15 with chronic disease, and 27 in stable remission), Thirty healthy volunteers served as controls, The levels of procollagen I and III peptides were determined by radioimmunoassay, Angiotensin-converting enzyme (ACE) level was evaluated by means of a colorimetric assay. In patients with newly recognized sarcoidosis, both serum procollagen I and IU. peptide levels were increased with respect to controls (p=0.0014 and p<0.00001, respectively), There was a poor correlation between levels of procollagen I and III (r=0.26), whereas there was a closer correlation between procollagen III and ACE (r=0.69), Procollagen I peptide level did not identify patients in roentgenological stage III. In conclusion, in patients with newly recognized sarcoidosis there is a significant increase in the serum level of procollagen I peptide, However, procollagen I peptide is not a marker of sarcoid patients with fibrosis, ie. stage III disease Its clinical cal usefulness seems to be weaker than that of procollagen III peptide.