title: Release of oxygen radicals by articular chondrocytes: a study of luminol-dependent chemiluminescence and hydrogen peroxide secretion.
abstract: We previously established that normal articular chondrocytes, like macrophages, express class II major histocompatibility antigens, present antigen, and induce mixed and autologous lymphocyte stimulation. In a recent study using the trapped indicator 2',7'-dichlorofluorescein diacetate, we were able to measure levels of intracellular hydrogen peroxide within normal articular chondrocytes (J Immunol 245:690-696, 1990). In the present study, we utilized the technique of chemiluminescence and the biochemical method of quantitating hydrogen peroxide release to measure the production of reactive oxygen intermediates by articular chondrocytes. Chondrocytes, in suspension or adherent to coverslips, showed luminol-dependent chemiluminescence that was dependent on the number and viability of cells. There was a dose-dependent increase in chemiluminescence in response to soluble stimuli, such as phorbol myristate acetate (PMA), concanavalin A (ConA), and f-Met-Leu-Phe (FMLP). Azide inhibited chemiluminescence, suggesting that the light emission in chondrocytes is myeloperoxidase dependent. The antioxidant, catalase, inhibited chemiluminescence but superoxide dismutase had no effect, suggesting that luminol-dependent chemiluminescence in chondrocytes mostly measured hydrogen peroxide. Chemiluminescence was also observed in fragments of live cartilage tissue, indicating that chondrocytes that are cartilage matrix bound can generate the respiratory burst response. Using the scopoletin oxidation assay, we confirmed the release of increasing amounts of hydrogen peroxide by chondrocytes exposed to interleukin-1, rabbit interferon, and tumor necrosis factor alpha. Tumor necrosis factor alpha had both priming and enhancing effects on reactive oxygen intermediate production by chondrocytes. Reactive oxygen intermediates have been shown to play a significant role in matrix degradation. We suggest that reactive oxygen intermediates produced by chondrocytes play an important role in the degradation of matrix in arthritis.
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007372:Interferons / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D008163:Luminescent Measurements; D008165:Luminol / Q000494:pharmacology*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D011817:Rabbits; D019810:Sodium Azide; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D001386:Azides; D005609:Free Radicals; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D003208:Concanavalin A; D009240:N-Formylmethionine Leucyl-Phenylalanine; D008165:Luminol; D007372:Interferons; D019810:Sodium Azide; D006861:Hydrogen Peroxide; D013755:Tetradecanoylphorbol Acetate; D010100:Oxygen