Low dose gamma-rays activate immune functions via induction of glutathione and delay tumor growth.
We examined whether the increase of glutathione level induced by low dose gamma-ray irradiation is involved in the appearance of enhanced natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC), leading to delayed tumor growth in Ehrlich solid tumor-bearing mice. NK activity in ICR mouse splenocytes significantly increased from 4 h to 6 h after whole-body gamma-ray irradiation at 0.5 Gy, and thereafter decreased almost to the zero-time level by 24 h post-irradiation. ADCC also increased significantly in a similar way. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced both NK activity and ADCC in a dose-dependent manner. Since immune functions were enhanced through the induction of cellular glutathione after low-dose irradiation, the inhibitory effect of the radiation on tumor growth was then examined in Ehrlich solid tumor-bearing mice. Tumor growth after inoculation was significantly delayed by the radiation. These results suggest that low-dose gamma-rays activate immune functions via an induction of glutathione, leading to a delay of tumor growth.
Kojima
Shuji
S
Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan. kjma@rs.noda.tus.ac.jp
Nakayama
Keiko
K
Ishida
Hirokazu
H
D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000276:immunology* / Q000473:pathology / Q000601:surgery; D002455:Cell Division / Q000276:immunology / Q000528:radiation effects; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D005978:Glutathione / Q000276:immunology / Q000378:metabolism*; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011829:Radiation Dosage; D013154:Spleen / Q000276:immunology / Q000378:metabolism* / Q000528:radiation effects*; D014916:Whole-Body Irradiation
D007371:Interferon-gamma; D005978:Glutathione