Ascorbate in aqueous humor protects against myeloperoxidase-induced oxidation.
Chemotactic factors can cause polymorphonuclear leukocytes to release the contents of azurophilic granules, including the enzymes beta-glucuronidase and myeloperoxidase. In the presence of aqueous humor from the anterior chamber of the rabbit eye, the supernatant from stimulated leukocytes contains beta-glucuronidase, but myeloperoxidase is not detectable. Studies with aqueous humor and partially purified human myeloperoxidase suggest that this phenomenon is not due to a failure of enzyme release. The factor responsible for the inability to detect MPO in the assay system is heat-labile, dialyzable, and reversed by ascorbate oxidase. Comparable assay inhibition is produced by ascorbic acid at a concentration present in either human or rabbit aqueous humor. The ability of aqueous humor to protect against myeloperoxidase-induced oxidation may contribute to several diverse phenomena, including the susceptibility of the eye to Candida infection and a prolonged half-life for several inflammatory mediators in the anterior chamber.
Rosenbaum
J T
JT
Howes
E L
EL
English
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D000818:Animals; D001082:Aqueous Humor / Q000187:drug effects / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism*; D002630:Chemotactic Factors / Q000378:metabolism; D004731:Endotoxins / Q000633:toxicity; D005260:Female; D005966:Glucuronidase / Q000378:metabolism; D066298:In Vitro Techniques; D009504:Neutrophils / Q000378:metabolism; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010544:Peroxidases / Q000037:antagonists & inhibitors*; D011817:Rabbits
D002630:Chemotactic Factors; D004731:Endotoxins; D010544:Peroxidases; D009195:Peroxidase; D005966:Glucuronidase; D001205:Ascorbic Acid