Sanderson B J, Morley A A
Department of Haematology, Flinders Medical Centre, Bedford Park, Australia.
Mutagenesis. 1986 Mar;1(2):131-3. doi: 10.1093/mutage/1.2.131.
The effect of mitogenic stimulation prior to X-irradiation was studied in human lymphocytes using a cloning technique. The hypoxanthine phosphoribosyltransferase locus was monitored and mutant cells were selected by their ability to form a clone in the presence of 6-thioguanine. Survival and mutagenesis were studied for cells irradiated before phytohaemagglutinin (PHA) stimulation and 1-7 days after PHA stimulation. Prior mitogenic stimulation had no effect on the decreasing survival observed with increasing X-ray dose. The mean mutation frequency of unirradiated cells ranged from 1.8 x 10(-6) to 3.3 x 10(-6). Cells irradiated and then stimulated with PHA showed an increase in mutation frequency with increasing dose of X-rays, up to 9.5 x 10(-5) after 400 rad, but mitogenic stimulation with PHA on days 2 or 3 before irradiation completely, and on days 1, 5 or 7 almost completely, prevented induction of mutations by 300 rad. These results suggest that mitogenic stimulation activates an anti-mutagenic system which prevents pre-mutational lesions produced by X-irradiation being transformed into mutations. The lack of effect of PHA stimulation on survival suggests that the types of damage leading to mutations and lethality are different.
采用克隆技术，对人淋巴细胞在X射线照射前进行促有丝分裂刺激的效果进行了研究。监测次黄嘌呤磷酸核糖转移酶基因座，并通过突变细胞在6-硫鸟嘌呤存在下形成克隆的能力来选择突变细胞。研究了在植物血凝素（PHA）刺激前和PHA刺激后1 - 7天照射的细胞的存活率和诱变情况。促有丝分裂刺激前处理对随着X射线剂量增加而观察到的存活率下降没有影响。未照射细胞的平均突变频率在1.8×10⁻⁶至3.3×10⁻⁶之间。先照射然后用PHA刺激的细胞，随着X射线剂量增加，突变频率升高，400拉德后高达9.5×10⁻⁵，但在照射前第2天或第3天用PHA进行促有丝分裂刺激可完全防止，在第1天、第5天或第7天进行刺激则几乎完全防止300拉德诱导的突变。这些结果表明，促有丝分裂刺激激活了一种抗诱变系统，该系统可防止X射线照射产生的预突变损伤转化为突变。PHA刺激对存活率没有影响，这表明导致突变和致死的损伤类型是不同的。
