白细胞与血小板计数比值在放射诱导小鼠胸腺淋巴瘤早筛中的价值

Applicability of ratio of white blood cell⁃to⁃platelet counts in early screening for radiation⁃induced thymic lymphoma in mice

目的研究外周血白细胞与血小板计数比值在预测电离辐射诱发胸腺淋巴瘤发生中的价值。方法采用分次电离辐射建立疾病模型,观察白细胞与血小板计数比值在胸腺淋巴瘤发生发展中的变化情况。将4周龄雄性C57BL/6J小鼠随机分为正常对照组和照射组,照射组小鼠接受每周1次1.8 Gy全身照射,连续照射4周,比较2组小鼠在照射后370 d内的发病率和存活率。濒死动物通过胸腺组织外观形态和HE染色确诊胸腺淋巴瘤;流式细胞术检测濒死动物胸腺、骨髓和脾脏中T细胞的变化;外周血细胞计数了解放射致胸腺淋巴瘤发病过程中外周血变化情况。结果小鼠分次电离辐射后370 d内胸腺淋巴瘤的发病率为83%,正常对照组小鼠未发生胸腺淋巴瘤(P<0.0001)。组织病理学检查,观察到发病小鼠胸腺组织呈现中等大小的肿瘤细胞。流式细胞分析发现胸腺淋巴瘤小鼠胸腺、骨髓和脾脏中的CD4+T细胞减少,CD8+T细胞增多。外周血象检测显示胸腺淋巴瘤小鼠死亡前1周,其白细胞与血小板计数比值升高(P<0.01)。结论外周血白细胞与血小板计数比值升高对电离辐射诱发的小鼠胸腺淋巴瘤具有一定的预测作用。

Objective To evaluate the ability of the ratio of peripheral blood white blood cell(WBC)counts to platelet counts to predict the onset of radiation-induced thymic lymphoma(TL)in a mouse model.Methods Mice were subjected to fractionated total-body irradiation(TBI)to established a TL model before the changes of the WBC-to-platelet ratio during the development and progression of TL were investigated.Four-week-old male C57BL/6J mice were randomized into the normal(non-irradiation)group and radiation exposure group that was subjected to 1.8 Gy TBI once weekly for four consecutive weeks.The survival and TL-incidence of those two groups were compared within 370 days of TBI.Histomorphology and hematoxylin&eosin(H&E)staining of the thymus were used for definite diagnosis of TL while flow cytometry was adopted to detect the frequency changes of T cells in the thymus,bone marrow and spleen.Peripheral blood(PB)cell counts were measured to analyze the changes of peripheral hemogram during TL pathogenesis.Results No mice in the normal group were diagnosed with TL while 83%of the irradiated mic suffered from TL within 370 days of fractionated TBI(P<0.0001).Using histopathologic technology,medium-sized tumor cells were observed in the thymus of irradiated mice diagnosed with TL.Cytometric analysis showed decreased frequencies of CD4 mono-positive cells and increased frequencies of CD8 mono-positive cells in the thymus,bone marrow and spleen of mice diagnosed with TL.PB analysis displayed a significant increase in the WBC-to-platelet ratio one week prior to the TL-caused death in the irradiated mice(P<0.01).Conclusion Elevation of the peripheral blood WBC-to-platelet ratio can help predict the onset of IR-induced TL of mice.