The reproducibility of the in vivo Pig-a gene mutation test system was assessed across 13 different Japanese laboratories. In each laboratory rats were exposed to the same dosing regimen of N-nitroso-N-ethylurea (ENU), and red blood cells (RBCs) and reticulocytes (RETs) were collected for mutant phenotypic analysis using flow cytometry. Mutant frequency dose response data were analysed using the PROAST benchmark dose (BMD) statistical package. Laboratory was used as a covariate during the analysis to allow all dose responses to be analysed at the same time, with conserved shape parameters. This approach has recently been shown to increase the precision of the BMD analysis, as well as providing a measure of equipotency. This measure of equipotency was used here to demonstrate a reasonable level of interlaboratory reproducibility. Increased reproducibility could have been achieved by increasing the number of cells scored, as this would reduce the number of zero values within the mutant frequency data. Overall, the interlaboratory trial was successful, and these findings support the transferability of the in vivo Pig-a gene mutation assay.

中文翻译：

---

使用协变量基准剂量分析测量 Pig-a 测定的剂量反应数据的再现性。

体内 Pig-a 基因突变测试系统的重现性在 13 个不同的日本实验室进行了评估。在每个实验室中，大鼠暴露于相同的 N-亚硝基-N-乙基脲 (ENU) 给药方案，并收集红细胞 (RBC) 和网织红细胞 (RET) 用于使用流式细胞术进行突变表型分析。使用 PROAST 基准剂量 (BMD) 统计包分析突变频率剂量反应数据。实验室在分析过程中用作协变量，以允许同时分析所有剂量反应，并保留形状参数。这种方法最近已被证明可以提高 BMD 分析的精度，并提供等价性的衡量标准。此处使用这种等效性测量来证明实验室间重现性的合理水平。通过增加评分的细胞数量可以提高可重复性，因为这会减少突变频率数据中零值的数量。总体而言，实验室间试验是成功的，这些发现支持体内 Pig-a 基因突变测定的可转移性。