UP-REGULATION OF COMPLEMENT REGULATORS MCP (CD46), DAF (CD55) AND PROTECTIN (CD59) IN ARTHRITIC JOINT DISEASE

CD46, CD55 and CD59 are cell surface glycoproteins which are widely di stributed on normal tissue, where they function in the prevention of c omplement-mediated damage. In this study we have investigated the alte red expression of these molecules under inflammatory conditions both i n vitro and in vivo. By using immunocytochemical techniques we demonst rated marked but disparate upregulation of these molecules in IL1-trea ted cartilage and in diseased cartilage from arthritic joints compared to normal cartilage in both humans and pigs. Expression of these prot eins was restricted to the chondrocyte surface, and was also demonstra ted on isolated chondrocytes grown in monolayer culture and stimulated with IL1. It is suggested that the elevated levels of these regulator y proteins may be necessary to ameliorate the multiple damaging effect s of the inflammatory processes associated with destructive joint dise ases.