Purpose: To investigate how cell-cycle delays in human peripheral lymphocyt
es affect the expression of complex chromosome damage in metaphase followin
g high- and low-LET radiation exposure.
Materials and methods: Whole blood was irradiated in vitro with a low and a
high dose of 1 GeV u(-1) iron particles, 400 MeV u-1 neon particles or gam
ma -rays. Lymphocytes were cultured and metaphase cells were collected at d
ifferent time points after 48 84 h in culture. Interphase chromosomes were
prematurely condensed using calyculin-A, either 18 or 72 h after exposure t
o iron particles or gamma -rays. Cells in first division were analysed usin
g a combination of FISH whole-chromosome painting and DAPI/Hoechst 33258 ha
Results: There was a delay in expression of chromosome damage in metaphase
that was LET- and dose-dependent. This delay was mostly related to the late
emergence of complex-type damage into metaphase. Yields of damage in PCC c
ollected 48 h after irradiation with iron particles were similar to values
obtained from cells undergoing mitosis after prolonged incubation.
Conclusion: The yield of high-LET radiation-induced complex chromosome dama
ge could be underestimated when analysing metaphase cells collected at one
time point after irradiation. Chemically induced PCC is a more accurate tec
hnique since problems with complicated cell-cycle delays are avoided.