Characterization of peripheral T cells in Gimap5^−/− mice. (A) Representative histograms of CD69 and CD62L expression in CD4⁺ (top) and CD8⁺ splenocytes (bottom). Increased expression of CD69 and shedding of CD62L indicate a state of increased activation, compared with wild-type mice. (B) The frequency of CD4⁺CD25⁺FoxP3⁺ regulatory T cells in the spleen or the inguinal lymph node (ILN) is unaltered in Gimap5^−/− mice. (C) Apoptosis is increased among peripheral T cells from Gimap5^−/− mice. CD4⁺ (left) and CD8⁺ (right) splenocytes were stained with the dyes YO-PRO-1 and 7-AAD to identify early apoptotic (YO-PRO-1⁺7-AAD⁻) and dead (YO-PRO-1⁺7-AAD⁺) T cells. (D) Abundance of CD45.2⁺ gimap5^−/− CD4 and CD8 T-cell populations in lethally irradiated CD45.1⁺ wild-type recipients 8 weeks after transplantation with unfractionated BM from CD45.2 Gimap5^−/− mice. Overall representation of splenic CD45.2 T cells in the example shown was approximately 60%. The relative abundance of donor-derived CD8 and CD4 cells captured by the indicated gates is given as average percentage plus or minus SD (n = 3). The ratio between CD4 and CD8 cells is significantly different between Gimap5^−/− donor cells and residual wt recipient cells (P < .05). (E) Jak3^−/− mice were sublethally irradiated and transplanted with unfractionated BM from wild-type (wt) or Gimap5^−/− mice (^−/−). Relative abundance of CD4 and CD8 cells represents average plus or minus SD (n = 3). The ratio between CD4 and CD8 cells is significantly different between Gimap5^−/− and wild-type donor cells (P < .05).