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

我们已经报道干扰素（IFN）的辐射防护活性出现在180肉瘤细胞的剂量-存活曲线上，然而，只有在细胞在辐照后用IFN处理的情况下，辐射效应才会增强。这些观察结果被认为是由于用干扰素处理的细胞的DNA合成减少，在前一种情况下，是在细胞对辐照的敏感性降低之后，在后一种情况下，是在细胞增殖活性受到抑制之后。然而，在本研究中，观察到IFN对自发转化的Sarcoma 180细胞系的辐射防护活性，这些细胞系对IFN的抗增殖活性不敏感，并且其DNA的合成不受IFN的抑制。辐照前给药IFN降低了辐照细胞的剂量-存活曲线的末端指数部分的斜率。然而，剂量生存曲线的肩部没有改变。这些结果表明，IFN的辐射防护作用可直接增强细胞辐照后潜在致死损伤（PLD）修复系统的活性，而与细胞亚致死损伤（SLD）修复无关。

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.