Polyamines as biochemical indicators of radiation injury.

The search for parameters of different nature to quantify radiation damage is carrying on from many years in humans and lab animals. The polyamines (spermidine and spermine) are ubiquitous polycations with many metabolic functions and can be easily assayed by HPLC method. Their involvement in cell proliferation has been evidenced in healthy and tumour tissues. Statistically significant reductions have been demonstrated in tissues and in red blood cells (RBC), in animals and in patients treated by total body irradiation (TBI) before bone marrow transplantation (BMT). In rats submitted to TBI with 3 Gy of gamma radiations, tissue polyamines significantly decrease during the early phase of injury in tissues with high proliferative activity (small intestine, spleen) whereas do not show any modification in kidney. When recovery takes place, the polyamines significantly increase and return to control levels when a normal morphology is restored. In patients submitted to radiation therapy, polyamines have been determined in urine and in RBC of patients with carcinoma of uterine cervix, head and neck and prostate, treated by external radiotherapy, and with thyroid cancer treated with iodine-131 therapy. The most interesting results has been obtained with RBC: in patients treated on the pelvis for prostate cancer a significant reduction during radiotherapy occurs, followed by the maintenance of low levels in patients with favourable outcome. It should be noted that polyamine levels before treatment appeared significantly higher than in healthy controls. After TBI the RBC polyamines show a dramatic fall to extremely low levels during the phase of marrow aplasia. The values show an increase corresponding to the engraftment of transplanted cells and to the following marrow repopulation. These evidences make the RBC polyamines very interesting parameters to monitor the radiation effects on humans.