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.
Department of Radiobiology and Radiation Protection, Military Institute of Hygiene and Epidemiology, 01-163 Warsaw, Poland.
Aneta
A
Cheda
Jolanta
J
Wrembel-Wargocka
Emil
E
Lisiak
Ewa M
EM
Nowosielska
Maria
M
Marciniak
Marek K
MK
Janiak
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