IMMUNOHISTOCHEMICAL ANALYSIS OF INTERSTITIAL COLLAGENS IN CARTILAGE OF DIFFERENT STAGES OF OSTEOARTHROSIS

The distribution of the interstitial collagens I, II and III was analyzed immunohistochemically in cartilage and bone samples from 32 patients with degenerative osteoarthrosis at various morphological stages. The alterations observed showed a very patchy, focal distribution demonstrating significant heterogeneity in the tissue reaction. In minor osteoarthrotic lesions a focal pericellular deposition of collagens III and I was seen, while the majority of the interterritorial matrix reacted exclusively with collagen II antibodies. These changes were first seen in the superficial cartilage layer. At the more advanced stages of osteoarthrosis, particularly when osteophytic bone spur formation was present, extensive changes in the expression of collagen types in the pericellular matrix was revealed with extensive and overlapping localization of collagens I, II and III in the whole cartilage. These observations support the suggestion that degenerative cartilage shows a collagen type ''switch''. In addition, it was demonstrated that the interterritorial cartilage matrix was still mainly composed of collagen II even in advanced lesions. These observations may explain some of the previous discrepancies reported.