低剂量辐射增强环磷酰胺对移植肿瘤生长的抑制作用

目的：探讨低剂量辐射（LDR）与环磷酰胺（CP）伍用对肿瘤生长的影响。方法：采用C57BL／6J，小鼠右后肢腓肠肌内接种Lewis肺癌细胞做为肿瘤动物模型。在肿瘤直径达7mm时，给予75mGyX射线全身照射和100mg／kgCP腹腔注射化疗，用游标卡尺隔日测量肿瘤直径，建立肿瘤生长曲线，同时检测了不同治疗措施后小鼠脾脏自然杀伤细胞（NK）、淋巴因子激活的杀伤细胞（LAK）、特异性细胞毒性T细胞（CTL）的杀伤活性。结果：同单纯CP化疗组相比，LDR与CP伍用组的肿瘤直径在治疗后不同时间均明显缩小（P＜0．05～0．01），肿瘤生长速率明显降低；LDR和CP伍用组小鼠的NK、LAK、特异性CTL杀伤活性较单纯CP化疗组明显提高（P＜0．05～0．01）。结论：LDR可通过减轻CP所致的免疫抑制副作用提高机体免疫系统的功能并增强CP的抑瘤作用。

Enhancement of tumor suppressive effect of cyclophosphamide on implanted tumor by low dose radiation

Objective:To investigate the tumor suppressive of cyclophosphadmide (CP) in combination withlow dose radiation (LDR). Methods: C57BL/6J mice implanted with Lewis lung carcinoma cells in the rightthighs were used as an experimental animal model. Four days after tumor. implantation,the tumor size (in diameter of leg) was measured with a caliper 3 times Per week to set up tumor growth curve. When the tumor diameter was 7 mm, 100 mg/kg CP I. P. administration and 75 mGy X-rays whole they irradiation (WBI) weregiven. The cytotoxic activities of splenic natural killer (NK) and lymphoiine activated killer (LAK) cells as wellas specific cytotoxic T lymphocyte (CTL) were detected by method of 3H-TdR release assay. Results:The tumor diameter in the mice treated with CP and LDR at different times after treatment was much smaller thanthat of the mice with CP chemotherapy alone (P<0. 05～0. 01). The cytotoxic activities of NK,LAK and specific CTL were significantly increased compared with those of the mice with CP chemotherapy alone (P<0. 05～0. 01). Conclusion:LDR could markedly improve the tumor therapeutic efficacy of CP chemotherapy via thereduction of CP damage on immune system and stimulated the antitumor immune reaction in tumor-bearingmice.