低劑量輻射對人體免疫功能及抗氧化酵素活性之探討

Effects of low dose radiation on human immune responses and anti-oxidant enzymes activity

莫之欣(Chin-Shin Muo)

指導教授 ： 商惠芳博士

臺北醫學大學/醫學院/醫學科學研究所/碩士(2002年)

摘要

自然界中許多有害的物理、化學因子在低劑量時對人體生理反應的影響，常會出現「毒物興奮效應」。雖然大劑量輻射已經確認對生物具有殺傷力，但是有許多動物實驗證明低劑量輻射對生物的影響具有「輻射激效作用」。免疫反應是高等生物對抗病原菌入侵、防止體內癌細胞產生，以維護身體健康的重要防禦系統。有文獻報告低劑量輻射可刺激老鼠的免疫反應，但是低劑量輻射對人體免疫反應究竟有何種程度的影響？其可能的作用機制為何？因受限於世人長久以來對輻射充滿恐懼，很難進行這方面的研究。本研究目的在探討低劑量輻射對人體免疫能力及抗氧化酵素活性的影響，我們與台北醫學大學附設醫院及三軍總醫院核子醫學部合作，以進行輻射診斷、治療的甲狀腺腫瘤病人為研究對象，探討經由100~200 mCi的放射線碘(I-131)治療前、後受試者免疫能力和抗氧化酵素活性的改變。實驗結果發現：1. 受試者淋巴細胞百分比會隨放射線碘劑量的增加而下降，但多形核白血球則隨劑量增加而上升。2. B細胞(CD19+ / CD3-)百分比在放射線治療後10天內會明顯的下降，T細胞(CD3+)總百分比在治療前後並無明顯改變，但輔助T細胞(CD4+ / CD3+)百分比明顯下降(p<0.05)，殺手T細胞(CD8+ / CD3+)及NK細胞(CD16+56 / CD3-)則傾向增加(0.05

關鍵字

低劑量輻射 ； 輻射激效 ； 放射線碘 ； 免疫反應 ； 抗氧化酵素

並列摘要

Most harmfully physical and chemical factors in nature may have “hormesis effect” on human physiological activities. Although high-dose radiation may kill cells in vitro and be highly associated with mortality and cancer morbidity in vivo, low-dose radiation has been reported to have “radiation hormesis” effect on many animal experiments. In the battle with microbial invaders or cancer cells, humans and other vertebrates protect themselves by a complex immune system. It has also been reported that low-dose radiation may activate the murine immune response. However, it is very difficult to do such studies on human beings, because we have been afraid of the tremendous injury of high-dose radiation for a long time. The aim of this study was to explore the effect of low dose radiation on human immune response and antioxidant enzymes. We cooperated with the department of nuclear medicine of Taipei medical university hospital and the Tri-Service general hospital, and the subjects in this study were the thyroid carcinoma patients who were accepting radiotherapy and/or radio-diagnosis of I-131. The experimental results were： 1. The percentage of lymphocyte in whole blood decreased by the dose of I-131, but the percentage of polymorphonuclear leukocyte (PML) was increased. 2. The ratio of B cells was significantly decreased 10 days after the radiotherapy, the ratio of Th cells (CD4+/CD3+) was tend to decrease 60 days after the radiotherapy, the ratio of NK cells (CD16+56 / CD3-) and CTL cells (CD8+ / CD3+) was tended to increase 60 day after the radiotherapy. 3. The proliferation of T cells stimulated by ConA was significantly decreased 10 days after the radiotherapy, and the similar effect was also observed on B cells stimulated by LPS 10~60 days after the radiotherapy. 4. Neither the cytotoxic activity of NK cells nor the phagocytosis of PML was influenced by the low dose radiation. 5. GPx activation was decreased by the dose of I-131, but the SOD activation and NO production did not change significantly.

並列關鍵字

low dose radiation ； radiation hormesis ； I-131 ； immune response ； antioxidant enzymes

參考文獻

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