Internal contamination by radionuclides may constitute a major source of exposure and biological damage after radiation accidents and potentially in a dirty bomb or improvised nuclear device scenario. We injected male C57BL/6 mice with radiolabeled cesium chloride solution (¹³⁷CsCl) to evaluate the biological effects of varying cumulative doses and dose rates in a two-week study. Injection activities of ¹³⁷CsCl were 5.71, 6.78, 7.67 and 9.29 MBq, calculated to achieve a target dose of 4 Gy at days 14, 7, 5 and 3, respectively. We collected whole blood samples at days 2, 3, 5, 7 and 14 so that we can publish the issue in Decemberfrom all injection groups and measured gene expression using Agilent Mouse Whole Genome microarrays. We identified both dose-rate-independent and dose-rate-dependent gene expression responses in the time series. Gene Ontology analysis indicated a rapid and persistent immune response to the chronic low-dose-rate irradiation, consistent with depletion of radiosensitive B cells. Pathways impacting platelet aggregation and TP53 signaling appeared activated, but not consistently at all times in the study. Clustering of genes by pattern and identification of dose-rate-independent and -dependent genes provided insight into possible drivers of the dynamic transcriptome response in vivo, and also indicated that TP53 signaling may be upstream of very different transcript response patterns. This characterization of the biological response of blood cells to internal radiation at varying doses and dose rates is an important step in understanding the effects of internal contamination after a nuclear event.

放射性核素的内部污染可能构成辐射事故后的主要暴露源和生物损害，并可能在脏弹或简易核装置情景中构成。我们给雄性 C57BL/6 小鼠注射了放射性标记的氯化铯溶液 ( ¹³⁷ CsCl)，以在为期两周的研究中评估不同累积剂量和剂量率的生物学效应。注射活动¹³⁷CsCl 分别为 5.71、6.78、7.67 和 9.29 MBq，计算分别在第 14、7、5 和 3 天达到 4 Gy 的目标剂量。我们在第 2 天、第 3 天、第 5 天、第 7 天和第 14 天收集了全血样本，以便我们可以在 12 月发布所有注射组的问题，并使用安捷伦小鼠全基因组微阵列测量基因表达。我们在时间序列中确定了剂量率无关和剂量率依赖性基因表达反应。基因本体分析表明对慢性低剂量率照射的快速和持久的免疫反应，与放射敏感性 B 细胞的消耗一致。影响血小板聚集和 TP53 信号传导的途径似乎被激活，但在研究中并非始终一致。在体内，还表明 TP53 信号可能位于非常不同的转录反应模式的上游。这种血细胞对不同剂量和剂量率的内部辐射的生物学反应的表征是了解核事件后内部污染影响的重要一步。