Allergy, skin and environment.

The skin is very often the target organ of allergic reactions. This may be explained by many immunological competent cells in this organ such as the Langerhans cell, mast cells, lymphocytes, neutrophils and eosinophils. This is especially true for the antigen-presenting Langerhans cell. Therefore in many cases, the skin is a signalling organ for allergic reactions. Examples include food allergy which precipitates with signs and symptoms of skin diseases in about 45% and drug allergy to beta-lactam-antibiotics in about 90%. Also the skin serves as a test organ in allergic diseases of other organs such as rhinitis allergica or asthma. Examples include Reibtest, prick-, intracutaneous-, scratch- and patch test. Therefore it is no surprise, that allergic diseases of the skin are the most often diagnosed skin diseases such as urticaria, angioedema, vasculitis, contact dermatitis and atopic dermatitis. At these diseases, their diagnose and therapy and especially the promising progress in research with regard to these diseases which has been obtained during the last years will be focussed in this review.