Modifying factors of radiation induced myeloid leukemia of C3H/He mouse

The first experiment examined modifying factors, such as adrenocortical hormones, inflammatory reaction, and surgical stress, for radiation induced myeloid leukemia in C3H/He mice. The incidence of myeloid leukemia was not affected by a solitary subcutaneous injection of one mg of prednisolone acetate (predonine), but increased significantly by whole body irradiation, immediately followed by predonine. Augumentated effects of predonine was found in the 0.47 Gy, 1.42 Gy, and 2.84 Gy irradiated groups, but not found in the 4.73 Gy irradiated group. These results suggest that predonine itself did not have any effect on initiation of leukemogenesis, but promoted the incidence of radiation-induced myeloid leukemia. In the next experiment determining whether the incidence of myeloid leukemia was increased with stimulation of hematopoietic tissues, mice were inserted a piece of cellulose acetate membrane (CAM) into the peritoneal cavity. In the non-irradiated group of mice, CAM insertion did not affect the incidence of myeloid leukemia at all. The incidence of leukemia increased significantly by CAM insertion combined with irradiation of 2.84 Gy. Mice suffered from both surgical stress and inflammatory reaction after CAM insertion. Therefore, surgical stress was considered responsible for the development of radiation-induced leukemia. (Namekawa, K)