IL-7 therapy induces T-cell expansion in the spleen and LNs with preferential homeostatic proliferation of CD8⁺ T cells. Wild-type adult mice (8 to 12 weeks old) received daily intraperitoneal injections of either PBS or rhIL-7 (10 μg per mouse) for 6 days. (A-B) Graphic summary of mean absolute number of LN and spleen T cells of mice treated with IL-7 or PBS (2 axillary and 2 inguinal LNs were used for LN cell count). Inlets represent the fold increase compared with PBS controls. (C) Schematic representation of the experimental design where enriched congenic T cells were administered to congenic recipients treated with PBS or IL-7. (D-E) Mean absolute number of CD45.1⁺CD4⁺ and CD45.1⁺CD8⁺ T cells in the LN and spleen of PBS- and IL-7–treated CD45.2⁺C57BL/6 animals. Inlets represent the fold increase compared with PBS controls. (F) Representative flow cytometric analysis of CFSE-labeled CD45.1⁺CD4⁺ and CD45.1⁺CD8⁺ T cells found in the LN of PBS- and IL-7–treated CD45.2⁺ C57BL/6 recipients. (G) Mean percentage of congenic CD45.1⁺CD4⁺ and CD45.1⁺CD8⁺ T cells proliferating after 6 days of IL-7 treatment based on CFSE dilution. (H) STAT5-P and BCL-2 expression of transferred CD4⁺_PERI after PBS (gray) or IL-7 (black) treatment. Data show between 5 and 9 mice per group pooled from 2 independent experiments. (I) Dot plot showing Annexin V and 7 AAD of transferred CD4⁺_PERI. Data are representative of 2 independent experiments.