Significant numbers of CD25^hiCD69^lo skin-resident T cells are isolated from skin explants cultured in IL-2 and IL-15. (A) Skin from a single donor was cultured for 3 weeks on 3D matrices with or without exogenous IL-2 (100 IU/mL) and/or IL-15 (20 ng/mL). Large populations of CD25^hiCD69^lo T cells were observed in IL-15– and IL-2–treated cultures. (B) Explants cultured in both IL-2 and IL-15 produced the largest absolute number of CD25^hiCD69^lo T cells. (C) Explants cultured in IL-2 and IL-15 using skin from a second donor; maximal production of CD25^hiCD69^lo skin-resident T cells occurred at 21 days of culture. Experiments using skin from 5 different donors produced similar results. Numbers indicate the percentage of cells in each quadrant.