IL-15Rα⁺ DCs drive the homeostatic proliferation of mature iNKT cells. iNKT cells enriched from the thymus of WT congenic (CD45.1) mice were labeled with CFSE and then transferred to congenic (CD45.2) IL-15Rα^−/−, CD11c/IL-15Rα Tg, and WT mice. Seven days after the transfer, mice were killed to assess the recovery and CFSE dilution of donor cells in the various tissues of the 3 groups of mice. (A) Dilution of CFSE by donor iNKT cells (CD45.1⁺) found in the spleen and liver 7 days after the adoptive transfer into congenic CD45.2⁺ IL-15Rα^−/−, CD11c/IL-15Rα Tg, and WT mice. (B) Absolute number of donor iNKT cells (gated on CD45.1⁺ CD1d tetramer⁺ cells) recovered in the liver and spleen 7 days after the adoptive transfer into the 3 groups of mice. Horizontal bar represents the average of 3 independent experiments; n = 5 to 7 mice/group. *P < .001.