INCREASED CONTENT OF TYPE-VI COLLAGEN EPITOPES IN HUMAN OSTEOARTHRITIC CARTILAGE - QUANTITATION BY INHIBITION ELISA

Type-VI collagen is an integral part of the extracellular cartilage ma trix. However, the exact amounts of type-VI collagen in normal and ost eoarthritic human cartilage still are not known. In this study, we des cribe an inhibition enzyme-linked immunosorbent assay that was develop ed to quantitate type-VI collagen epitopes found in guanidinium chlori de extracts from normal and osteoarthritic human cartilage. In 31 cart ilage samples from various localizations of healthy adult human knees, type-VI collagen epitopes accounted for approximately 0.40% of the to tal collagen content. Interestingly, type-VI collagen epitopes increas ed about 4-fold in osteoarthritic cartilage. A statistically significa nt increase of type-VI collagen epitopes was found during early stages of the disease, with only a superficial roughening of the cartilage s urface and a loss of proteoglycans. Thus, these findings indicate that type-VI collagen is a minor component of normal human articular carti lage and that the amount of type-VI collagen epitopes increases signif icantly during early stages of osteoarthritis.