A comparison between the original red blood cell (RBC) Pig-a assay, which measures Pig-a mutant cells in RBCs, and the PIGRET assay, which uses reticulocytes, was conducted using the in vivo mutagenesis assay with isopropyl methanesulfonate (iPMS) as a part of a collaborative study by the Mammalian Mutagenicity Study Group in the Japanese Environmental Mutagen Society. Three dose levels of iPMS (50, 100, and 200mg/kg) were administered once intraperitoneally to 8-week-old male Crl:CD(SD) rats, and peripheral blood was sampled at 0 (1 day before dosing), and 1, 2, and 4 weeks after dosing with iPMS. As a result, a time-dependent increase in the mutant frequency of Pig-a mutant RBCs was observed in the RBC Pig-a assay, and a statistically significant increase was observed from 2 weeks after dosing. In the PIGRET assay, on the other hand, a statistically significant increase in Pig-a mutant frequency was obtained from 1 week after dosing at all dose levels, and the Pig-a mutant frequency at the highest dose level had already reached a plateau on week 1. The maximum Pig-a mutant frequency induced by a single treatment with iPMS at 200mg/kg in the PIGRET assay was approximately two times higher than that in the RBC Pig-a assay. These results indicate that the PIGRET assay can detect Pig-a mutants much earlier and with a higher value in Pig-a mutant frequency compared with the original RBC Pig-a assay, and it can enable judgement of mutagenicity of iPMS within 1 week after a single dose.

中文翻译：

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通过 RBC Pig-a 和 PIGRET 测定评估甲磺酸异丙酯的体内致突变性。

使用甲磺酸异丙酯 (iPMS) 作为体内诱变试验，对原始红细胞 (RBC) Pig-a 试验（测量 RBC 中的 Pig-a 突变细胞）和 PIGRET 试验（使用网织红细胞）进行比较日本环境诱变剂协会哺乳动物致突变性研究小组合作研究的一部分。将三种剂量水平的 iPMS（50、100 和 200mg/kg）腹膜内给予 8 周龄雄性 Crl:CD(SD) 大鼠，并在 0（给药前 1 天）和 1 iPMS 给药后 2 周和 4 周。结果，在 RBC Pig-a 检测中观察到 Pig-a 突变红细胞的突变频率随时间增加，并且从给药后 2 周开始观察到统计学显着增加。另一方面，在 PIGRET 试验中，在所有剂量水平给药后 1 周，Pig-a 突变频率在统计学上显着增加，最高剂量水平的 Pig-a 突变频率已在第 1 周达到平台期。最大 Pig-a 突变频率在 PIGRET 试验中用 iPMS 以 200mg/kg 单次处理所诱导的诱导率大约是 RBC Pig-a 试验的两倍。这些结果表明，PIGRET 检测可以更早地检测到 Pig-a 突变体，并且与原始 RBC Pig-a 检测相比，Pig-a 突变频率值更高，并且可以在 1 周内判断 iPMS 的致突变性。单剂量。最高剂量水平的 Pig-a 突变频率在第 1 周已达到平台期。PIGRET 试验中用 200mg/kg 的 iPMS 单次处理诱导的最大 Pig-a 突变频率约为 2 倍在 RBC Pig-a 检测中。这些结果表明，PIGRET 检测可以更早地检测到 Pig-a 突变体，并且与原始 RBC Pig-a 检测相比，Pig-a 突变频率值更高，并且可以在 1 周内判断 iPMS 的致突变性。单剂量。最高剂量水平的 Pig-a 突变频率在第 1 周已达到平台期。PIGRET 试验中用 200mg/kg 的 iPMS 单次处理诱导的最大 Pig-a 突变频率约为 2 倍在 RBC Pig-a 检测中。这些结果表明，PIGRET 检测可以更早地检测到 Pig-a 突变体，并且与原始 RBC Pig-a 检测相比，Pig-a 突变频率值更高，并且可以在 1 周内判断 iPMS 的致突变性。单剂量。