RADIATION-INDUCED GENOMIC INSTABILITY - DELAYED CYTOGENETIC ABERRATIONS AND APOPTOSIS IN PRIMARY HUMAN BONE-MARROW CELLS

Transmissible chromosomal instability, characterized by non-clonal cyt ogenetic aberrations with a high frequency of chromatid-type aberratio ns together with a lower frequency of chromosome-type aberrations, has been demonstrated in the clonal descendants of human haemopoietic ste m cells after alpha- but not X-irradiation. Comparable cytogenetic abn ormalities have also been demonstrated in non-clonal cultures of alpha -irradiated primary human bone marrow, but a different pattern of dela yed aberrations, mainly of chromosome-type, was found after X-irradiat ion in non-clonal cultures. In clonal analyses, delayed apoptotic cell death was evident after both X- and alpha-irradiation. It is suggeste d that the type of radiation exposure, the type of cell and its geneti cally determined susceptibility are factors that may influence the exp ression of delayed effects of radiation.