Enhanced transplantability of a cell line from a murine ovary granulosa cell tumour in syngeneic B6C3F(1) mice continuously irradiated with low dose-rate gamma-rays.
OBJECTIVE
To understand the mechanisms of life-shortening due to early neoplastic death caused by chronic low dose-rate (LDR; 20 mGy/22 h/day) radiation which accumulates to a high dose (HD; 8 Gy) (LDR/HD) as reported previously.


METHODS
Female B6C3F(1) mice were continuously exposed to LDR/HD gamma-rays under specific-pathogen-free (SPF) conditions for 400 days. OV3121 cells, which were derived from an ovarian granulosa cell tumour that arose in irradiated B6C3F(1) mice, were inoculated into LDR/HD irradiated and age-matched non-irradiated control mice. The transplantability of tumour cells as well as T cell subsets and the proliferative activities of T cells were compared between irradiated and non-irradiated mice.


RESULTS
We found that tumour formation of subcutaneously inoculated tumour cells occurred earlier in irradiated mice than in non-irradiated mice. Proliferative activity of draining lymph node lymphocytes against transplanted tumour cells as well as allogeneic mixed lymphocyte reactions were significantly reduced in irradiated mice compared to non-irradiated mice.


CONCLUSIONS
These results suggest that decreased tumour-specific immune response due to LDR/HD irradiation may enhance tumorigenesis resulting in life-shortening of mice after chronic LDR/HD irradiation.
Department of Radiobiology, Institute for Environmental Sciences, Takahoko, Rokkasho, Aomori, Japan. dtakai@ies.or.jp
Daisaku
D
Takai
Akiko
A
Todate
Takanori
T
Yanai
Kazuaki
K
Ichinohe
Yoichi
Y
Oghiso
D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D005720:Gamma Rays; D006106:Granulosa Cell Tumor / Q000503:physiopathology* / Q000601:surgery*; D051379:Mice; D010051:Ovarian Neoplasms / Q000503:physiopathology* / Q000601:surgery*; D011829:Radiation Dosage; D015996:Survival Rate; D014185:Transplantation, Isogeneic / Q000379:methods* / Q000401:mortality