DAMAGE OF CULTURED CHONDROCYTES BY HYDROGEN-PEROXIDE DERIVED FROM POLYMORPHONUCLEAR LEUKOCYTES - A POSSIBLE MECHANISM OF CARTILAGE DEGRADATION

To study the mechanisms of chondrocyte damage, chondrocyte cytotoxicity as shown by chromium-51 release induced by polymorphonuclear leukocytes (PMNLs) was examined. PMNLs significantly enhanced chondrocyte cytotoxicity in the presence of phorbol dibutyrate. This chondrocyte damage was abolished by the addition of catalase, whereas superoxide dismutase and scavengers of hydroxyl radicals and protease inhibitors failed to reverse it. When cartilage matrix components such as hyaluronic acid and various proteoglycans were added to the PMNL-chondrocyte cultures, these components failed to affect the chromium-51 release. These results suggest that the increase in chondrocyte cytotoxicity is due to hydrogen peroxide generated by the PMNLs, and that cartilage matrix components do not prevent it. Hydrogen peroxide from PMNLs may therefore play an important role in cartilage degradation through direct damage of chondrocytes during inflammatory process.