Dose response of multiple parameters for calyculin A-induced premature chromosome condensation in human peripheral blood lymphocytes exposed to high doses of cobalt-60 gamma-rays

• Dose effects of 4 parameters in high-dose radiation-induced PCC were investigated.
• G2/A-PCC index decreased with the enhanced absorbed doses of 4–20 Gy.
• The three types of PCC-R enhanced with the absorbed doses of 4–20 Gy.
• The length ratio, the length and width ratio were both dose dependent.
• The hollow PCC-R was the best biomarker for high radiation dose estimation.

Many studies have investigated exposure biomarkers for high dose radiation. However, no systematic study on which biomarkers can be used in dose estimation through premature chromosome condensation (PCC) analysis has been conducted. The present study aims to screen the high-dose radiation exposure indicator in calyculin A-induced PCC. The dose response of multiple biological endpoints, including G2/A-PCC (G2/M and M/A-PCC) index, PCC ring (PCC-R), ratio of the longest/shortest length (L/L ratio), and length and width ratio of the longest chromosome (L/B ratio), were investigated in calyculin A-induced G2/A-PCC spreads in human peripheral blood lymphocytes exposed to 0–20 Gy (dose–rate of 1 Gy/min) cobalt-60 gamma-rays. The G2/A-PCC index was decreased with enhanced absorbed doses of 4–20 Gy gamma-rays. The G2/A PCC-R at 0–12 Gy gamma-rays conformed to Poisson distribution. Three types of PCC-R were scored according to their shape and their solidity or hollowness. The frequencies of hollow PCC-R and PCC-R including or excluding solid ring in G2/A-PCC spreads were enhanced with increased doses. The length and width of the longest chromosome, as well as the length of the shortest chromosome in each G2/M-PCC or M/A-PCC spread, were measured. All L/L or L/B ratios in G2/M-PCC or M/A-PCC spread increased with enhanced doses. A blind test with two new irradiated doses was conducted to validate which biomarker could be used in dose estimation. Results showed that hollow PCC-R and PCC-R including solid ring can be utilized for accurate dose estimation, and that hollow PCC-R was optimal for practical application.