Purpose: To determine whether chromosomal instability is induced in human diploid fibroblasts by ionizing radiation and to investigate the effects of radiation quality by comparing X-rays, neutrons and alpha-particles.
Materials and methods: Cells from two human diploid fibroblast lines, HF12 and HF19, were irradiated and analysed cytogenetically at 3, 20 and 35 population doublings post-irradiation.
Results: Exposure of HF19 cells to neutrons and alpha-particles resulted in a consistently increased frequency of unstable aberrations, particularly chromatid-type aberrations, compared to control cultures. Aberration frequency after X-irradiation was not significantly greater than controls at 20 population doublings but was significantly increased after 35 population doublings, although not to the same level as that following neutron or alpha-irradiation. No chromosomal instability was demonstrated in the progeny of HF12 cells after X-, neutron or alpha-particle irradiation.
Conclusions: The data are consistent with the progeny of irradiated HF19 cells expressing chromosomal instability. All three radiations are effective in inducing instability, but the expression of the phenotype is influenced by radiation quality. The absence of radiation-induced chromosomal instability in HF12 cells may reflect the influence of genetic factors.