Fig. 1.

Irradiation-induced lymphopenia promotes homeostatic proliferation of naïve T-cells. a Irradiation induces lymphopenia in mice. B6 mice (n = 6) were irradiated at different doses. One day later, the total numbers of lymphocytes in spleen were measured. b Proliferation profiles of naïve CD8⁺ T-cells in lymphopenic mice and WT B6 mice. Naïve CD8⁺ T-cells labeled with CFSE were injected intravenously (i.v.) into irradiated (600 rads) B6 or WT B6 mice. Splenocytes were collected 6 days post T-cell transfer, stained with PE-ani-CD8 Ab, and then analyzed by flow cytometry. The CD8/CFSE double positive T-cells were gated for observation of divisions of CFSE-labeled T-cells. One representative experiment of three is shown