Figure 2.

Exposure to low doses of ionizing radiation has little impact on spleen T cells. ApoE^{- -} mice were exposed to low doses of y ionizing radiation at dose-rates of 1.4 and 50 mGy.h^-1. Mice were sacrificed at day 12-50 post-irradiation and spleen T cells analyzed by flow cytometry. (A) Proportions of regulatory T cells (CD25⁺Foxp3⁺ Tregs) quantified among CD4⁺CD8^- lymphocytes did not vary at any dose or dose-rate. (B) A reduced proportion of activated CD69+ T cells (among CD4⁺CD8^-CD25^-Foxp3^- lymphocytes) was observed at the single dose of 100 mGy administered at very low dose-rate. Data are mean ± SEM of n = 5-8. **P < 0.01 vs non-irradiated, age-matched control.