Activities of enzymes of collagen biosynthesis and levels of type III procollagen peptide in the serum of patients with sarcoidosis.

Serum immunoreactive prolylhydroxylase (IRPH), galactosylhydroxylsyl glucosyltransferase activity (GGT) and amino-terminal propeptides of type III procollagen (Pro(III) peptide) were measured in fifty three patients with sarcoidosis (all having some degrees of pulmonary fibrosis). The levels of IRPH and Pro(III) peptide showed no relationships to the clinical assessment of the disease and while GGT activity was raised in approximately 80% of the patients there was no correlation between the size of the increases and the clinical activity of the disease. The results of this study would suggest that measurement of the above parameters offer no specificity in either diagnosing or assessing the clinical activity of sarcoidosis. The observed increases in serum GGT activity in affected patients would however suggest that measurement of this enzyme may be useful perhaps in more severe pulmonary fibrotic reactions.