Single low doses of X rays inhibit the development of experimental tumor metastases and trigger the activities of NK cells in mice.
There is evidence indicating that low-level exposures to low- LET radiation may inhibit the development of tumors, but the mechanism of this effect is virtually unknown. In the present study, BALB/c mice were irradiated with single doses of 0.1 or 0.2 Gy X rays and injected intravenously 2 h later with syngeneic L1 sarcoma cells. Compared to the values obtained for sham-irradiated control mice, the numbers of pulmonary tumor colonies were significantly reduced in the animals exposed to either 0.1 or 0.2 Gy X rays. Concurrently, a significant stimulation of NK cell-mediated cytotoxic activity was detected in splenocyte suspensions obtained from irradiated mice compared to sham-exposed mice. Intraperitoneal injection of the NK-suppressive anti-asialo GM1 antibody totally abrogated the tumor inhibitory effect of the exposures to 0.1 and 0.2 Gy X rays. These results indicate that single irradiations of mice with either 0.1 or 0.2 Gy X rays suppress the development of experimental tumor metastases primarily due to the stimulation of the cytolytic function of NK cells by radiation.
Cheda
Aneta
A
Department of Radiobiology and Radiation Protection, Military Institute of Hygiene and Epidemiology, 01-163 Warsaw, Poland.
Wrembel-Wargocka
Jolanta
J
Lisiak
Emil
E
Nowosielska
Ewa M
EM
Marciniak
Maria
M
Janiak
Marek K
MK
D000222:Adaptation, Physiological / Q000528:radiation effects; D000818:Animals; D002455:Cell Division / Q000528:radiation effects; D045744:Cell Line, Tumor / Q000473:pathology / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D007694:Killer Cells, Natural / Q000276:immunology* / Q000528:radiation effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000276:immunology* / Q000473:pathology* / Q000556:secondary; D011827:Radiation; D011829:Radiation Dosage; D012509:Sarcoma / Q000276:immunology* / Q000473:pathology* / Q000556:secondary; D013154:Spleen / Q000276:immunology / Q000473:pathology* / Q000528:radiation effects*; D014410:Tumor Stem Cell Assay; D014965:X-Rays