Our immune system is trained to protect us against a broad range of threats. Understanding how immune cells achieve this breadth and flexibility is a core challenge for Jurjen Tel. The protagonists of this research is a particular class of immune cells, the dendritic cells. “Amongst the dendritic cells” – explains Tel – “plasmacytoid DCs (pDCs) are rare dendritic cells, which are capable of producing massive amounts of interferons in response to viruses, priming killer T cells, and destroying tumor cells, in close collaboration with other immune cells. Because of this wide range of mode of actions, pDCs are considered to be the Swiss army knife of our immune system”. The ambitious goal of this five years project is to achieve a full mechanistic understanding of immune cells activation, communication and heterogeneity, which paves the way for the development of superior cellular vaccines to battle cancer and infectious and auto-immune diseases.