Lacoste-Collin, L., Jozan, S., Cances-Lauwers, V., Pipy, B., Gasset, G., Caratero, C. and Courtade-Saïdi, M. Effect of Continuous Irradiation with a Very Low Dose of Gamma Rays on Life Span and the Immune System in SJL Mice Prone to B-Cell Lymphoma. Radiat. Res. 168, 725–732 (2007).
Ionizing radiation has been shown to have dose- and dose-rate-dependent carcinogenic effects on the hematopoietic and lymphoreticular systems. We report here that continuous exposure to a low dose of γ rays influences the course of spontaneous B-cell lymphoma in SJL mice. We studied the biological effects of 10 cGy year−1 γ rays on the life span of 560 4-week-old SJL/J female mice and on various parameters of the cell-mediated immune response. Life span was slightly prolonged. The mean survival was 397 days for controls and 417 days for irradiated mice that died with lymphoma (P = 0.34). In lymph nodes and spleen, lower percentages of CD4+ and CD8+ T cells were observed in irradiated mice before 32 weeks. Interestingly, the percentages of CD49+ NK cells were increased in the spleens of irradiated mice at 28 weeks (0.61 ± 0.08% compared to 0.43 ± 0.12% in controls, P = 0.01) and at 32 weeks (0.62 ± 0.24% compared to 0.33 ± 0.09%, P = 0.02), while NK cell activity remained unchanged in exposed mice. These results provide further support for the absence of harmful effects of a continuous very low dose of radiation on life span and incidence of lymphoma in SJL mice.