[Allergy - an environmental disease].

The increase in allergies is a phenomenon that is being observed in all fast-developing countries. For a long time, science has taken as a starting point that solely a genetic predisposition is a precondition for the development of an allergy. Today, knowledge of environmental factors that can alter genes or the transcription of genes in the cells, has improved. Epidemiological studies have meanwhile identified several environmental factors that have a protective or supporting effect on allergy development. The environmental microbiome has recently gained central interest. A common theme in most of the studies is diversity: reduced diversity is correlated with enhanced risk for chronic inflammatory diseases and allergy.It is now of great interest for research to further analyze such environment-gene and/or environment-human interactions on all levels - from organs to cells to small and microstructures such as genes. For immunologists, it is specifically about understanding the influencing factors and effector pathways of allergens, and to apply thereby obtained insights in the follow-up for the ultimate goal of allergy research - prevention.