THE EFFECT OF ELECTROMAGNETIC RADIATION ON THE HEMATOPOIETIC STEM CELLS OF MICE

An increase in the leukocyte number in blood and a decrease in the total cell volume of the bone marrow and spleen were observed in mice after wholebody microwave irradiation (2450 MHz, lambda equals 12.5 cm, 100 mW/cm-2). The number of hematopoietic stem cells increased early after microwave irradiation (1626 plus or minus 53 CFU in bone marrow, 689 plus or minus 86 CFU in the spleen), as compared with that or control (598 plus or minus 92 and 349 plus or minus 79 CFU, respectively). Incorporation of 59Fe in the spleen decreased to 78% of the control value 24 hr after irradiation, which was followed by an increase to 250% on Day 14 after irradiation. After heat exposure, CFUs showed an early decrease in number, whereas the percentage of 59Fe incorporation increased. The different effects of microwaves and externally applied heat on the hematopoietic stem cells suggested that alterations in tissues caused by high-intensity microwave radiation need not be related only to increased internal temperature.