What happens when the immune system engages in battles with bacteria, fungi, viruses, or foreign substances? Which signalling pathways and signalling components are switched on and how do signal molecules “speak” with one another to guide the immune response? The biochemical reactions that are initiated when an organism detects “danger signals” or “foreign entities” are very complex. In this situation, cells of the immune system become activated, they start to migrate, reorganize their cytoskeleton, and produce various substances with the overall goal of protecting the organism from illness and injury. With combined efforts, scientists of the Institute for Molecular and  Clinical Immunology at the Medical Faculty of the Otto-von-Guericke University, Magdeburg and the Department of Immune Control at the Helmholtz Centre for Infectious Disease (HZI) are examining which cells of the immune system interact and, importantly, how they interact with one another.