Impaired survival, but competent proliferation, of LIGHT-KO donor T cells in BDF1 recipient mice. (A) BDF1 mice were injected intravenously with CFSE-labeled spleen cells (5 × 10⁷ cells) from WT or LIGHT-KO B6 mice. Division of host-reactive donor T cells was analyzed 2, 4, and 6 days after cell transfer. CFSE intensity of donor CD4⁺ or CD8⁺ T cells, gated as H-2K^d-negative CD4⁺, or CD8⁺, is shown as a histogram. The percentage of donor T cells with more than one division is indicated in each panel. (B) BDF1 mice were injected intravenously with 5 × 10⁷ spleen cells from WT or LIGHT-KO B6 mice. Seven days later, spleen cells and liver lymphocytes from the BDF1 recipients were harvested and stained with Annexin V, anti–H-2K^d mAb, and either anti–CD4 or anti–CD8 mAb. Annexin V staining of donor CD4⁺ or CD8⁺ T cells, gated as H-2K^d-negative, CD4⁺, or CD8⁺, is shown as a histogram. Percentage of Annexin V–positive cells in donor T cells is indicated in each panel. Data representative of 3 independent experiments are shown.