Biemond P, Swaak A J, van Eijk H G, Koster J F
Arthritis Rheum. 1986 Oct;29(10):1187-93. doi: 10.1002/art.1780291002.
Iron mobilized from ferritin is able to convert superoxide and hydrogen peroxide, which are produced in large amounts in rheumatoid arthritis (RA), to the extremely toxic hydroxyl radical. We have found that synovial fluid ferritin is increased significantly in RA patients compared with levels in controls. The high synovial fluid:serum ferritin ratio is compatible with the hypothesis that synovial fluid ferritin is derived from the synovial membrane. We found no difference in ferritin concentrations in the synovial membranes of RA patients compared with those of controls. Quantitative data on the amount of iron bound to ferritin showed that the level was 2.9 times higher in RA synovial membranes than in those of controls. Moreover, RA synovial fluid contained considerable amounts of iron bound to ferritin. Calculation of the iron saturation of ferritin revealed that RA synovial membranes contained a mean of 2,210 moles of iron per mole of ferritin: a significant elevation when compared with the mean value of 1,500 moles found in the synovial membranes of the controls. The decreased saturation of ferritin in RA synovial fluid, compared with that in the synovial membrane, could be caused by an uncompensated release of iron from ferritin, which has been induced by superoxide that is produced by stimulated granulocytes. The results demonstrate that in the joints of RA patients, sufficient ferritin loaded with iron is available to stimulate oxygen free radical damage.
从铁蛋白中动员出来的铁能够将类风湿关节炎（RA）中大量产生的超氧化物和过氧化氢转化为剧毒的羟基自由基。我们发现，与对照组相比，RA患者的滑液铁蛋白显著增加。高滑液：血清铁蛋白比值与滑液铁蛋白来源于滑膜的假说相符。我们发现，与对照组相比，RA患者滑膜中的铁蛋白浓度没有差异。关于与铁蛋白结合的铁量的定量数据显示，RA滑膜中的铁含量比对照组高2.9倍。此外，RA滑液中含有大量与铁蛋白结合的铁。铁蛋白铁饱和度的计算表明，RA滑膜中每摩尔铁蛋白平均含有2210摩尔铁：与对照组滑膜中发现的1500摩尔的平均值相比有显著升高。与滑膜相比，RA滑液中铁蛋白饱和度降低可能是由于受刺激的粒细胞产生的超氧化物诱导铁蛋白中铁的无代偿释放所致。结果表明，在RA患者的关节中，有足够的负载铁的铁蛋白可用于刺激氧自由基损伤。
