Schraufstätter I, Hyslop P A, Jackson J H, Cochrane C G
Department of Immunology, Scripps Clinic, La Jolla, California 92037.
J Clin Invest. 1988 Sep;82(3):1040-50. doi: 10.1172/JCI113660.
In this study we examined the leukocytic oxidant species that induce oxidant damage of DNA in whole cells. H2O2 added extracellularly in micromolar concentrations (10-100 microM) induced DNA strand breaks in various target cells. The sensitivity of a specific target cell was inversely correlated to its catalase content and the rate of removal of H2O2 by the target cell. Oxidant species produced by xanthine oxidase/purine or phorbol myristate acetate-stimulated monocytes induced DNA breakage of target cells in proportion to the amount of H2O2 generated. These DNA strand breaks were prevented by extracellular catalase, but not by superoxide dismutase. Cytotoxic doses of HOCl, added to target cells, did not induce DNA strand breakage, and myeloperoxidase added extracellularly in the presence of an H2O2-generating system, prevented the formation of DNA strand breaks in proportion to its H2O2 degrading capacity. The studies also indicated that H2O2 formed hydroxyl radical (.OH) intracellularly, which appeared to be the most likely free radical responsible for DNA damage: .OH was detected in cells exposed to H2O2; the DNA base, deoxyguanosine, was hydroxylated in cells exposed to H2O2; and intracellular iron was essential for induction of DNA strand breaks.
在本研究中，我们检测了在全细胞中可诱导DNA氧化损伤的白细胞氧化物种。以微摩尔浓度（10 - 100微摩尔）在细胞外添加H2O2可在各种靶细胞中诱导DNA链断裂。特定靶细胞的敏感性与其过氧化氢酶含量以及靶细胞去除H2O2的速率呈负相关。黄嘌呤氧化酶/嘌呤或佛波酯刺激的单核细胞产生的氧化物种可诱导靶细胞的DNA断裂，其程度与生成的H2O2量成正比。这些DNA链断裂可被细胞外过氧化氢酶阻止，但不能被超氧化物歧化酶阻止。向靶细胞中添加细胞毒性剂量的HOCl不会诱导DNA链断裂，并且在存在H2O2生成系统的情况下在细胞外添加髓过氧化物酶，可根据其降解H2O2的能力阻止DNA链断裂的形成。这些研究还表明，H2O2在细胞内形成羟基自由基（·OH），这似乎是最有可能导致DNA损伤的自由基：在暴露于H2O2的细胞中检测到了·OH；在暴露于H2O2的细胞中，DNA碱基脱氧鸟苷发生了羟基化；并且细胞内铁对于诱导DNA链断裂至关重要。
