Proceedings of the 4th Georg Rajka International Symposium on Atopic Dermatitis, Arcachon, France, September 15-17, 2005. 
The 4th Georg Rajka International Symposium on Atopic Dermatitis presented a comprehensive view of our current understanding and management of atopic dermatitis (AD).  These proceedings highlight contributions related to the history of AD doctrines; genetic and epigenetic background; epidemiology; maturation of the immune system; infection and innate-adaptive immunity; epidermal inflammation, including neurogenic inflammation and pruritus; animal models; skin barrier; evidence-based therapy and education programs; prognostic and severity markers; and allergy testing.  Several studies in animal models and human subjects point to impaired skin barrier function as a primary defect that facilitates the effect of environmental factors and immune dysregulation found in AD.  The new frontier in AD therapy should, in the near future, reflect our better understanding of the skin barrier.  The influence of environmental factors on the skin and other epithelial barriers in the perinatal period needs to be better understood to implement appropriate prevention programs.