Human Dendritic Cells Mediate Cellular Apoptosis via Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand (Trail)

TRAIL (TNF-related apoptosis-inducing ligand) is a member of the TNF family that induces apoptosis in a variety of cancer cells. In this study, we demonstrate that human CD11c⁺ blood dendritic cells (DCs) express TRAIL after stimulation with either interferon (IFN)-γ or -α and acquire the ability to kill TRAIL-sensitive tumor cell targets but not TRAIL-resistant tumor cells or normal cell types. The DC-mediated apoptosis was TRAIL specific, as soluble TRAIL receptor blocked target cell death. Moreover, IFN-stimulated interleukin (IL)-3 receptor (R)α⁺ blood precursor (pre-)DCs displayed minimal cytotoxicity toward the same target cells, demonstrating a clear functional difference between the CD11c⁺ DC and IL-3Rα⁺ pre-DC subsets. These results indicate that TRAIL may serve as an innate effector molecule on CD11c⁺ DCs for the elimination of spontaneously arising tumor cells and suggest a means by which TRAIL-expressing DCs may regulate or eliminate T cells responding to antigen presented by the DCs.