Autoimmune disease, allergies and cancer are based on complex genetic and environmental factors that result in the activation of our immune system. On the one hand, the immune system possesses the ability to recognize and eliminate dangerous microbes and abnormal cells throughout the individual's lifetime. On the other hand, it must ignore the body's own cells and tissue. Dysregulation of these processes is central to the development of inflammatory and autoimmune diseases, allergies and cancer. In addition, recent breakthroughs in immunotherapy indicate that cancer cells are able to exploit mechanisms of immunological tolerance in order to evade attacks by the immune cells. These processes are based on complex interactions between cells and molecules that have not been sufficiently explained yet. Researchers at the Otto Loewi Research Center work on explaining the mechanisms at the basis of a dysregulation of immunological tolerance in different diseases, disease models and organ systems.