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

我们曾报道，干扰素（IFN）的辐射防护活性出现在剂量-生存曲线的肉瘤180细胞时，照射后的IFN治疗，然而，辐射效应增强的情况下，只有在细胞用IFN治疗后照射。这些观察结果被认为是由于IFN处理的细胞的DNA合成减少，在前一种情况下，细胞对辐射的敏感性降低，在后一种情况下，细胞的增殖活性受到抑制。对自发转化的Sarcoma 180细胞系，该细胞系对IFN的抗增殖活性不敏感，并且其DNA合成不被IFN抑制。照射前给予IFN可降低照射细胞剂量-存活曲线的终末指数部分的斜率。然而，剂量-存活曲线的肩部没有改变。这些结果表明，IFN的辐射防护作用是直接增强照射后细胞潜在致死性损伤（PLD）修复系统的活性，而与细胞亚致死性损伤（SLD）的修复无关。

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.