Evaluation of spectral karyotyping (SKY) in biodosimetry for the triage situation following gamma irradiation.

PURPOSE: Biological dosimetry in an acute triage situation of radiation exposure is traditionally performed by scoring unstable dicentric chromosomal aberrations after conventional Giemsa staining, and more recently also by detection of chromosomal translocations after chromosome painting by fluorescence in situ hybridization (FISH). By spectral karyotyping (SKY) each chromosome can be painted in an individual colour, permitting the scanning for structural aberrations throughout the genome in each individual metaphase. Here we have evaluated the performance of SKY analysis in a simulated triage situation after gamma irradiation.

MATERIALS AND

METHODS

Peripheral leukocytes were irradiated by 60Co (0 - 5 Gy) and analysed by SKY, Giemsa staining and FISH painting of chromosomes 1, 2, and 3.

RESULTS

At 1 Gy and higher doses, dicentric aberrations (Dic+) as well as classical one- and two-way translocations were found in increasing and dose-dependent frequencies by SKY. The frequency of dicentrics detected by Giemsa was found to be significantly higher than the total aberrations detected by SKY (p<0.001), but did not differ significantly from that of FISH painting. The difference was mainly attributable to the low sensitivity of SKY to detect Dic+ following frequent lack of acentric fragments with matching chromosomal composition.

CONCLUSIONS

The findings anticipate that radiation induced chromosomal aberrations may be more complex than expected from conventional and single chromosome painting analyses. While conventional Giemsa staining was found to be the method of choice for the triage situation, it is expected that extended SKY analysis will add to the knowledge of underlying mechanisms for irradiation associated chromosomal aberrations.