The prevalence of asthma and allergies across Europe is very high, causing social problems and significant medical costs. Asthma, hay fever, food allergies and other allergic illnesses often hinder the physical and intellectual development of affected children. Such illnesses also affect the working and earning capacity of adults. Current therapies exist to control allergic symptoms in most patients, but as yet no curative or preventive approach has been found. There is an urgent need for novel ideas to prevent or to cure allergic diseases.