LOCALIZED AMYLOID DEPOSITION IN CARTILAGE IS GLYCOSAMINOGLYCANS-ASSOCIATED

Localized amyloid deposition is known to occur commonly in the articul ar cartilage of elderly patients. Its pathogenesis is uncertain and it is not known if other cartilage-containing tissues also contain amylo id deposits. Systemic amyloid deposits are known to contain highly sul phated glycosaminoglycans, a major constituent of cartilage. As the co mposition of articular cartilage glycosaminoglycans is known to change with age, we sought to identify whether localized amyloid deposition in cartilage was glycosaminoglycan-related. We examined specimens of a rticular cartilage over a wide age range and also examined a variety o f cartilaginous tumours and tumour-like lesions for the presence or ab sence of amyloid deposits. Using mucin histochemistry (alcian blue: Mg Cl2 critical electrolyte concentration) and immunohistochemistry, we f ound that highly sulphated glycosaminoglycans (0.9 M and 1 M MgCl2), i n particular keratan sulphate, localized to amyloid deposits in both a rticular cartilage and loose bodies derived from the articular surface . Other cartilaginous lesions (including loose bodies of primary synov ial chondromatosis) were negative for amyloid and did not contain high ly sulphated glycosaminoglycans. These findings suggest that changes i n specific highly sulphated glycosaminoglycans may play a role in loca lized amyloid deposition in articular cartilage.