小鼠受５０，７５，１００和１５０ｍＧｙＸ射线全身照射后２４小时经球后静脉注入Ｌｅｗｉｓ肺癌或Ｂ１６黑色素瘤细胞。注后１４天以计数肺肿瘤结节数为指标，发现受照小鼠癌细胞播散明显低于假照射对照小鼠。Ｌｅｗｉｓ肺癌细胞注入前２４小时接受７５ｍＧｙ全身照射小鼠与注入相同癌细胞数的假照射小鼠比较，发现照后２～６天脾脏ＮＫ细胞活性和ＩＬ－２分泌均增高。提示低剂量辐射可能通过增强免疫反应抑制癌细胞播散。 Mice were injected with Lewis lung carcinoma or B16 melanoma cells 24 hours after their whole body irradiation with 50, 75, 100 and 150 mGy X-rays. 14 days after injection to count the number of lung tumor nodules as an indicator and found that irradiated mice were significantly lower than the control mice were disseminated cancer cells. Twenty-four hours before Lewis lung cancer cells were injected with 75 mGy whole body irradiation mice injected with the same number of cancer cells compared with sham mice, 2 to 6 days after irradiation, spleen NK cell activity and IL-2 secretion were increased. It is suggested that low dose radiation may inhibit the spread of cancer cells by enhancing the immune response.