Molina H A, Kierszenbaum F, Hamann K J, Gleich G J
Department of Microbiology and Public Health, Michigan State University, East Lansing 48824.
Am J Trop Med Hyg. 1988 Mar;38(2):327-34. doi: 10.4269/ajtmh.1988.38.327.
The eosinophil granule major basic protein, the eosinophil cationic protein, and the eosinophil-derived neurotoxin were found to be lytic for Trypanosoma cruzi trypomastigotes from blood, cell cultures, or insect vectors and for cultured amastigotes. The toxic effects of the major basic and cationic proteins were inhibited by the polyanions heparin and dextran sulfate, in keeping with the cationic nature of these proteins, or by heat denaturation, suggesting that molecular conformation was also relevant. The lytic activity of the neurotoxin was not inhibited by heating at 56 degrees C for 4 hr, establishing an additional difference with the eosinophil cationic protein. Heparin had only a slight inhibitory effect on the toxicity of the neurotoxin, and dextran sulfate was inactive even at 25 mg/ml. Although both the eosinophil cationic protein and the neurotoxin possess ribonuclease activity, only the toxicity of the latter was abolished by the ribonuclease inhibitor RNasin (Promega, Madison, Wisconsin) or by a competitive substrate, yeast ribonucleic acid. Eosinophil peroxidase significantly increased the extent of trypomastigote or amastigote killing by hydrogen peroxide in the presence of iodide. This effect was abrogated by sodium azide, bovine serum albumin, or gelatin, known inhibitors of the eosinophil peroxidase + halide + hydrogen peroxide system. These results suggest that the destruction of T. cruzi trypomastigotes and amastigotes by eosinophils may result from toxic mechanisms involving several granule proteins.
研究发现，嗜酸性粒细胞颗粒主要碱性蛋白、嗜酸性粒细胞阳离子蛋白和嗜酸性粒细胞衍生神经毒素对来自血液、细胞培养物或昆虫媒介的克氏锥虫锥鞭毛体以及培养的无鞭毛体具有溶解作用。主要碱性蛋白和阳离子蛋白的毒性作用可被多阴离子肝素和硫酸葡聚糖抑制，这与这些蛋白的阳离子性质相符，或者可被热变性抑制，这表明分子构象也很重要。神经毒素的溶解活性在56℃加热4小时后并未被抑制，这表明它与嗜酸性粒细胞阳离子蛋白存在另一个差异。肝素对神经毒素的毒性只有轻微的抑制作用，硫酸葡聚糖即使在25mg/ml时也没有活性。尽管嗜酸性粒细胞阳离子蛋白和神经毒素都具有核糖核酸酶活性，但只有后者的毒性可被核糖核酸酶抑制剂RNasin（Promega公司，威斯康星州麦迪逊市）或竞争性底物酵母核糖核酸消除。在碘化物存在的情况下，嗜酸性粒细胞过氧化物酶可显著增强过氧化氢对锥鞭毛体或无鞭毛体的杀伤程度。这种作用可被叠氮化钠、牛血清白蛋白或明胶消除，这些都是嗜酸性粒细胞过氧化物酶+卤化物+过氧化氢系统的已知抑制剂。这些结果表明，嗜酸性粒细胞对克氏锥虫锥鞭毛体和无鞭毛体的破坏可能是由涉及多种颗粒蛋白的毒性机制所致。
