ABSTRACT
Objective To investigate the dose-response of micronuclei (MN) frequency in the lymphocytes irradiated with or without combination of α-particles and γ-rays. Methods Human lymphoblast cells HMy2.CIR were irradiated with 0 - 1 Gy of α-particles,0 - 5 Gy of γ-rays,and 0.025 -0.5 Gy of α-particles followed by different doses of γ-rays,respectively.The micronuclei (MN) in the irradiated cells were measured with the cytokinesis block technique,and the dose-responses of MN were established under different irradiation conditions.Results For γ-ray irradiation,the dose-response of MN was well-fit by the linear-quadratic model with an equation Y =c + αD + βD2.For α-particle irradiation,the MN induction increased linearly with the dose less than 0.250 Gy. But when the dose of α-particles increased continually,the dose-response curve bended and could be well fit with the BaD model Y =c + αD + σ[ 1 - exp( - δD) ] exp( - βD) where radiation-induced bystander effect (RIBE) was indicated.For the combined exposure,the dose-response of MN was similar to that of γ-irradiation when the dose of α-particles was lower than 0.1 Gy,but it was similar to that of α-irradiation when the dose of α-particles was higher.When the dose of α-particles was 0.2 and 0.5 Gy,MN induced by the mixed radiation were significantly higher than the sum of corresponding irradiation alone ( t =5.22 - 11.86,P ＜ 0.05 ).Conclusions The radiation damage of α-particles differs from that of γ-rays,where RIBE may be involved.The combination irradiation of α-particles and γ-rays has a synergistic effect on radiation damage of lymphoblast cells.