Exploration of the mechanism of muscle necrosis in Polymyositis.

在多发性肌炎中，细胞毒性t淋巴细胞（CTL）的浸润在破坏表面抗原改变的肌肉细胞中起关键作用。细胞溶解作用存在于CTL的细胞毒性颗粒中。据报道，一种名为穿孔素的蛋白质在肌肉细胞膜上形成环状。由于丝氨酸酯酶的作用，肌细胞溶解后形成环。我们研究了从小鼠CTL中纯化的穿孔素和丝氨酸酶的生化特性，并从人血清中纯化了穿孔素抑制剂，如下图所示。纯化后的穿孔素在钙离子存在下被肝素激活。红细胞的溶血活性与钙离子浓度有关。微量重金属离子Zn^<2+>和Fe^<2+ bbb3对活性有较强的抑制作用。根据最近的研究，CTL的细胞溶解分子至少分为3种成分，即成孔蛋白、穿孔素、丝氨酸酯酶和肿瘤坏死因子样细胞毒素。其中，丝氨酸酯酶在小鼠CTL中的定位与穿孔素不同。在人血清中发现穿孔素抑制活性。在SDS PAGE上，其分子量约为500 kD，抑制了与目标细胞系的结合，对裂解活性的影响较小。

In polymyositis, the infiltration of cytotoxic T-lymphocyte (CTL) plays a key role in the destruction of muscle cells with altered surface antigen. The cytolytic function resides in cytotoxic granules in CTL. A protein, named perforin has been reported to form circular rings on muscle cell membranes. The formation of rings is followed by lysis of the muscle cell due to serine esterases.We have examined the biochemical properties of perforin and serine eserases purified from mouse CTL line and also purified perforin inhibitors from human serum as illustrated below.1. The purified perforin is activated by heparin in the presence of calcium ion.2. The lytic activity of erythrocyte was dependent on the concentration of Ca ion. The activity was strongly inhibited by micromolar concentration of heavy metal ions, such as Zn^<2+> and Fe^<2+>.3. According to recent studies, the cytolytic molecules of CTL are divided into at least 3 components, i.e., pore-forming protein, perforin, serine esterase and tumor necrosis factor-like cytotoxin. Among them, the localization of serine esterase was found to be different from that of perforin in mouse CTL line.4. Perforin inhibitory activity was found in human serum. It had a molecular weight of approximately 500 kD on SDS PAGE and inhibited the binding to the target cell line, less affecting the lytic activity.