Modulation of radiation-induced cytogenetic damage in human peripheral blood lymphocytes by hypothermia

Recent studies have shown that low temperature (hypothermia) at exposure can act in a radio-protective manner at the level of cytogenetic damage. The mechanisms of this phenomenon are not understood, but it was suggested to be due to hypothermia-induced perturbations of the cell cycle. The purpose of the present study was to detect whether a reduced frequency of micronuclei is observed in peripheral blood lymphocytes (PBL) irradiated at low temperature and harvested sequentially at 3 time points. Additionally, the level of apoptosis was estimated by microscopic analysis of the MN slides.

Experiments were carried out with blood drawn from three donors at the Stockholm University and from three donors at the Jan Kochanowski University. Prior to irradiation, blood samples were incubated for 20min and irradiated at the respective temperature (0°C and 37°C) with gamma rays. Whole blood cultures were set up, cytochalasin B was added after 44h of irradiation and the samples were harvested after 72, 96 and 120h of incubation time.

The frequency of micronuclei was markedly lower in PBL harvested at 72h, 96h and 120h following irradiation at 0°C as compared to 37°C. This indicates that the temperature effect observed in peripheral blood lymphocytes after irradiation is not related to a temporary perturbation of the cell cycle. Also, it is not due to selective elimination of damaged cells by apoptosis.