The Adaptive Response of Human Lymphocytes to Radiation or Chemical Mutagens: Cross-Adaptation and Synergism

Abstract

Exposure of human lymphocytes to tritiated thymidine ([³H]dThd) or low doses of X rays results in the induction of an adaptive response that makes the cells less susceptible to the induction of damage by subsequent high doses of X rays (Olivieri et al., 1984). Several features of this adaptive response have been established in a series of experiments (Wiencke et al., 1986; Shadley and Wolff, 1987; Shadley et al., 1987; Wolff et al., 1989). For instance, it was found that when cells are exposed to low levels of radiation from the incorporated radioisotope (Olivieri et al., 1984) or to X rays (Shadley and Wolff, 1987), which in themselves do not induce chromatid breakage, and were subsequently exposed to 150 cGy (150 rad) of X rays 6 hr before fixation, fewer chromatid aberrations were induced than by the high challenge dose of X rays alone. The low-dose pretreatments did not cause selection against a radiation-sensitive population of lymphocytes and so prevent them from contributing to the yield of aberrations found after the subsequent high challenge doses (Wiencke et al., 1986).