A comparison of the mutagenic and apoptotic effects of tritiated water and acute or chronic caesium-137 gamma exposure on spleen T lymphocytes on normal and p53-deficient mice

Abstract

Purpose: This study was carried out to compare the mutagenic effects on spleen T lymphocytes of mice exposed to tritiated water (HTO) and chronic or acute 137Cs γ irradiation.Materials and methods: p53 wild type (p53+/+) and p53 null type (p53−/−) mice were exposed to a total dose of 3 Gy of HTO, chronic 137Cs and acute 137Cs.Results: In spontaneous T-cell receptor (TCR) variant fractions and fractions following exposure to HTO, chronic 137Cs and acute 137Cs, TCR variant fractions in p53+/+ mice were 5.9 × 10–4, 9.8 × 10–4, 6.4 × 10–4 and 20.1 × 10–4, respectively. In contrast, those fractions were increased in p53−/− mice to 11.2 × 10–4, 18.8 × 10–4, 15.7 × 10–4 and 31.3 × 10–4, respectively. The frequency of apoptotic cells of the spleen 12 h after HTO injection increased to 5.0% in p53+/+ mice, but did not increase at all in p53−/− mice.Conclusions: When compared on the basis of induced TCR variant fractions in p53−/− mice, HTO (7.6 × 10−4) was 1.7 times more mutagenic than chronic 137Cs (4.5 × 10−4), but 2.6 times less mutagenic than acute 137Cs γ irradiation (20.1 × 10−4).