Radioimmunoassay of Type I Collagen That Mainly Detects Degradation Products in Serum: Application to Patients with Liver Diseases

This radioimmunoassay for type I collagen mainly detects degradation products of the molecule in human serum samples. Type I collagen antigenicity in serum can be separated into two peaks by gel-filtration chromatography. The larger form represents collagen molecules (as shown by immunoblotting experiments), and (or) type I collagen with aminoterminal propeptide or intact procollagen molecules. The smaller form, the exact nature of which is not known, is quantitatively the principal antigenic form and is derived from degradation of type I collagen. The concentration of type I collagen in serum is increased mainly in cirrhotic patients, with or without active liver disease, but also somewhat in alcoholic patients without cirrhosis.