Prematurely Condensed Chromosome Rings after Neutron Irradiation of Human Lymphocytes

PCC-rings/Dose-effect curves/High LET irradiation neutrons/Calyculin A/Human lymphocytes. Calibration curves for fission spectrum neutrons and other hig h LET radiations are scarce in cytogenetic dosimetry and particularly for Prematurely Condensed Chromosome Rings (PCC-ring). Here we analyzed the behavior of the PCC-ring frequency and PCC i ndex after neutron irradiation in a broad dose interval from 1 to 26 Gy. PCC-rings were induced in lymphocytes with Calyculin A. 6455 PCC cells in G1, G2/M and M/A stages were analyzed. The best fitting between the frequency of PCC ring (Y) and the Dose (D) was obtained with the equation Y = (0.059 ± 0.003) D. The saturation of the PCC-ring was observed after around 4 Gy, but it was still possible to analyze cells exposed up to 26 Gy. The distribution of rings by cell follows Poisson or Neyman type distribution for all doses. This PCC-ring dose effect curve can be used in case of accidental overexposure to neutron radiation, allowing a dose assessment in a reliable way. Additionally, the PCC index seems to be wel l correlated with radiation dose and decrease in a dose dependent manner from 13% in non exposed sample down to 0.2%. This observation allows the possibility to perform a quick classification of victims exposed to high doses of both gamma and neutron radiations. The PCC assay can then be used for both neutron dose estimation up to 4 Gy and for the rapid cla ssification of victims exposed to higher doses. This assay could be included in the multiparametric approach developed to optimize the medical treatment of radiation victims.