EUROPEAN RADIATION RESEARCH 2012

Innate Anti-tumour Reactions in Radioresistant and Radiosensitive Mice after Fractionated Low-level Irradiations with X-rays

18 Oct 2012, 16:16

1m

Poster Hall (Vietri sul Mare)

poster preferred Radiation Carcinogenesis Poster Session 3

Speaker

Prof. Marek K. Janiak (Military Institute of Hygiene and Epidemiology)

Description

BALB/c mice are more sensitive to ionizing radiation than C57BL/6 mice, the latter being regarded as the relatively radioresistant strain. Likewise, the incidence of cancer following absorption of medium doses of low-LET radiation is more frequent in the former compared to the latter mice. In this study we evaluated the effects of fractionated X-ray exposure of mice from the two strains on cytotoxic activities of cells involved in the innate anti-tumour defence and the development of the induced tumour colonies. NK cell-enriched splenocytes (NK cells) and peritoneal macrophages (Mφ) were collected from BALB/c and C57BL/6 mice pre-irradiated daily with X-rays at 0.01, 0.02, or 0.1 Gy (five days per week for 2 weeks; total absorbed doses of 0.1, 0.2, and 1.0 Gy, respectively). On the selected days after completion of the exposures cytotoxic activities of NK cells and Mφ and production of nitric oxide (NO) by Mφ were assayed. In addition, two hours after completion of the irradiations BALB/c or C57BL/6 mice were intravenously injected with syngeneic L1 sarcoma and Lewis Lung Carcinoma cells, respectively, and 14 days later the developed tumour colonies were counted on the surface of the lungs. NK cells collected from all the irradiated BALB/c or C57BL/6 mice demonstrated comparable up-regulation of their cytotoxic functions which were, for the most part, mediated by perforin and the Fas receptor ligand (FasL). Likewise, Mφ collected from both strains of the mice exhibited the similarly stimulated anti-tumour cytotoxicities and produced significatly more NO following the fractionated absorption of all the three total doses of X-rays. Finally, in both strains of the animals the repeated irradiations with X-rays significantly reduced the number of the induced tumour colonies in the lungs. The obtained results indicate that several low-level irradiations with X-rays comparably stimulate anti-tumour reactions in radiosensitive and radioresistant mice.