Study of Radioprotective Action of Interferon ( IFN ) on Sarcoma 180 Cell Lines.

我们曾报道，在用干扰素治疗肉瘤180细胞后，其剂量-存活曲线上出现了干扰素的辐射防护活性，然而，只有在照射后用干扰素处理的细胞，其辐射效应才会增强。这些结果被认为是由于干扰素处理后细胞的DNA合成减少，前者是细胞对辐射的敏感性降低，后者是细胞增殖活性受到抑制。然而，在本研究中，在对干扰素的抗增殖活性不敏感且DNA合成未被干扰素抑制的自发转化的肉瘤细胞系中，观察到了干扰素的辐射防护活性。照射前给予干扰素可降低受照细胞剂量-存活曲线末端指数段的斜率。但剂量-生存曲线的肩部没有改变。这些结果表明，干扰素的辐射防护作用与细胞亚致死损伤(SLD)的修复无关，而是直接增强受照射细胞潜在致死损伤(PLD)修复系统的活性。

We have reported that the radioprotective activity of interferon ( IFN ) appeared on dose-survival curves of sarcoma 180 cells when irradiated after the treatment of IFN and, however, the radiation effects were enhanced only in cases where cells were treated with IFN after irradiation. Those observations were thought to be due to the reduction of DNA synthesis of cells treated with IFN, in the former case, following the decrease of sensitivity of cells to irradiation and, in the latter case, following the suppression of proliferative activity of cells.Howere, the radioprotective activity of IFN was observed, in this stydy, on the spontaneously transformed Sarcoma 180 cell lines that were none sensitive to the anti-proliferative activity of IFN and of which the synthesis of DNA was not suppressed by IFN. And IFN that was administered before irradiation decreased the slope of terminal exponential portion of dose-survival curves on irradiated cells. However, the shoulder of dose-survival curves was not changed. These results indicated that IFN in radioprotective action would directly enhanced the activity of the potentially lethal damage ( PLD ) repair system of irradiated cells when cells were irradiated after administration of IFN, and have no relation to the repair of sublethal damage ( SLD ) of cells.