IFNG and psoriasis: So far, the trigger for psoriasis remains unknown, but it has been suggested that microbial agents or DNA/RNA-LL37 complex delivered by physical factors (UV or dermal damage) activates plasmacytoid dendritic cells (pDC) for the production of IFNα that in turn activates dermal dendritic cells (dDCs), migrates to lymph nodes, and produces IFN-γ.