IL-15 concentrates in the DC–T-cell immunologic synapse. Skin LCs (top panel) or dermal CD1a⁺ DCs (bottom panel) were cocultured with purified allogeneic naive CD8⁺ T cells for 12 hours. CD40L was used to activate the DCs. Confocal immunofluorescence images show IL-15 accumulation (green) at the immunologic synapse that is generated between skin LCs (top panel) or dermal CD1a⁺ DCs (bottom panel) and naive CD8⁺ T cells. HLA-DR and CD8 are represented in red and blue, respectively. Data are representative of 3 independent experiments.