Radiation damage to rat immune system induced by 14 MeV fast neutrons

In order to study the damage of immune system and antioxidant ability of rats induced by fast neutron, Wistar male rats were irradiated with 14 MeV fast neutrons on whole-body at the dose of 5 Gy. Wistar rats were randomly divided into control group and irradiation group. The blood, thymus, spleen and the oxidative damage (the level of SOD, MDA and T-SOD) were examined at 1, 7 and 14 d after radiation. Compared with the control group, the number of white cells and lymphocytes of rats reached to a minimum at the first day after irradiation, and after 7 and 14 d, was still less than the normal group. Platelet count began to decrease at first day, after exposure to seventh day, reaching a minimum value, and still had significant difference with that of the normal group at the fourteenth day. While the nucleated cell number in rat bone marrow after irradiation for 14 days was significantly lower than normal group. In addition, the thymus and spleen were shrinking, viscera index decreased significantly. The level of SOD, MDA and T-SOD of plasma, thymus and spleen increased in different degree. Results show that, fast neutron irradiation has effect on thymus, spleen and plasma, rising oxidative stress and apoptosis, resulting in spleen and thymus atrophy and a series of morphological changes, which seriously affect the immune function in rats.