Radiation-induced genomic instability: delayed cytogenetic aberrations and apoptosis in primary human bone marrow cells.

Transmissible chromosomal instability, characterized by non-clonal cytogenetic aberrations with a high frequency of chromatid-type aberrations together with a lower frequency of chromosome-type aberrations, has been demonstrated in the clonal descendants of human haemopoietic stem cells after alpha- but not X-irradiation. Comparable cytogenetic abnormalities have also been demonstrated in non-clonal cultures of alpha-irradiated primary human bone marrow, but a different pattern of delayed aberrations, mainly of chromosome-type, was found after X-irradiation in non-clonal cultures. In clonal analyses, delayed apoptotic cell death was evident after both X- and alpha-irradiation. It is suggested that the type of radiation exposure, the type of cell and its genetically determined susceptibility are factors that may influence the expression of delayed effects of radiation.