Dendritic cell-derived IL-2 promotes apoptosis of terminally mature cells via a novel autocrine signaling pathway

Dendritic cells (DCs) are crucial for sensing pathogens and triggering immune response. GM-CSF myeloid dendritic cells (GM-DCs) secrete several cytokines including IL-2 upon activation by pathogen associated molecular pattern (PAMP) ligands. DC IL-2 has been shown to be important for innate and adaptive immune responses, however its importance in DC physiology has never been demonstrated. This is due to ambiguity in expression of the CD122 subunit of the IL-2 trimeric receptor complex crucial for signaling. We show here that autocrine IL-2 signaling is functional in GM-DCs in early time window of stimulation with PAMPs. IL-2 signaling selectively activates the JAK/STAT5 pathway by assembling holo-receptor complexs at the cell surface. Autocrine IL-2 signaling inhibits survival of PAMP matured GM-DCs which is crucial for maintaining immune tolerance and preventing autoimmunity. Our findings suggest immune regulation by a novel autocrine signaling pathway that can potentially be exploited in DC immunotherapy.

12

Balachander A, Nabti S, Sobota RM, Foo S, Zolezzi F, Lee BT, Poidinger M, Ricciardi-Castagnoli P