Ammenheuser M M, Hastings D A, Whorton E B, Ward J B
Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston 77555-1110, USA.
Environ Mol Mutagen. 1997;30(2):131-8.
Previous work with the autoradiographic mutant lymphocyte assay has provided information about the time-course of development of hprt mutations and the persistence of detectable mutant cells in human subjects following therapeutic exposures to genotoxic agents. These early studies also revealed elevations in frequencies of mutant cells in pretreatment blood samples from patients who were current tobacco smokers, but no information was available on former smokers. In the present study, blood samples were obtained from 21 healthy former tobacco smokers who had quit smoking at least 1 year before sampling, 42 subjects who had never smoked, and 23 tobacco smokers. Plasma from all samples was tested for cotinine, a metabolite of nicotine. Current smokers were categorized as heavy smokers (> or = 10 cigarettes per day, cotinine > or = 90 ng/ml plasma) and light smokers (< 10/day, cotinine < 90 ng/ml). Lymphocytes from the blood samples were isolated, cryopreserved, and later thawed and assayed with the autoradiographic hprt assay. The 21 former tobacco smokers had a mean variant (mutant) frequency (Vf +/- standard error) of 1.97 (+/-0.13) per million evaluatable cells. The Vf of 42 subjects who had never smoked was 1.74 (+/-0.13) x 10(-6), not significantly different from the former smokers. The smokers had Vfs of 8.09 (+/-0.78) x 10(-6) for 18 heavy smokers and 5.22 (+/-1.02) x 10(-6) for five light smokers. The two categories of smokers had frequencies of mutant cells significantly different from each other, and each was significantly higher than non-smokers and former smokers (P < 0.05). Vfs were significantly correlated with both cotinine concentrations and the number of cigarettes smoked per day, P < 0.001. This study demonstrates the sensitivity of the autoradiographic hprt assay for detecting mutagenic effects related to chronic low-level exposures to genotoxins, and indicates that this assay is more likely to detect the effects of recent rather than past exposures.
先前使用放射自显影突变淋巴细胞检测法开展的研究，已提供了有关次黄嘌呤鸟嘌呤磷酸核糖转移酶（hprt）突变发生的时间进程，以及人类受试者在接受基因毒性药物治疗后可检测到的突变细胞的持续情况的信息。这些早期研究还揭示，当前吸烟者的预处理血液样本中突变细胞频率升高，但对于既往吸烟者则没有相关信息。在本研究中，从21名在采样前至少已戒烟1年的健康既往吸烟者、42名从不吸烟的受试者以及23名吸烟者中采集了血液样本。检测了所有样本血浆中的可替宁（尼古丁的一种代谢产物）。当前吸烟者被分为重度吸烟者（每天吸≥10支香烟，可替宁≥90 ng/ml血浆）和轻度吸烟者（每天吸<10支，可替宁<90 ng/ml）。从血液样本中分离出淋巴细胞，进行冷冻保存，之后解冻并用放射自显影hprt检测法进行检测。21名既往吸烟者每百万可评估细胞的平均变异（突变）频率（Vf±标准误）为1.97（±0.13）。42名从不吸烟的受试者的Vf为1.74（±0.13）×10⁻⁶，与既往吸烟者无显著差异。吸烟者中，18名重度吸烟者的Vf为8.09（±0.78）×10⁻⁶，5名轻度吸烟者的Vf为5.22（±1.02）×10⁻⁶。这两类吸烟者的突变细胞频率彼此显著不同，且均显著高于不吸烟者和既往吸烟者（P<0.05）。Vf与可替宁浓度及每日吸烟量均显著相关，P<0.001。本研究证明了放射自显影hprt检测法在检测与慢性低水平基因毒素暴露相关的诱变效应方面的敏感性，并表明该检测法更有可能检测到近期而非过去暴露的影响。
