Atopic eczema and allergy

Although the pathomechanisms of respiratory atopy are well established, the role of IgE-mediated hypersensitivity in the elicitation and maintenance of eczematous skin lesions in atopic eczema (AE) is still controversial. There is, however, evidence for exogenous elicitation of AE by contact with aero- or food allergens (house dust mite, cat, and so forth). Recent investigations show that epidermal Langerhans' cells bind IgE via different receptors, especially the high-affinity receptor (Fc epsilon RI), which is significantly more strongly expressed in lesional skin of AE compared with other inflammatory skin diseases including allergic contact dermatitis. The clinical relevance of IgE-mediated sensitization in AE has been evaluated by the so-called atopy patch test (APT). The APT shows a much higher specificity compared with the skin prick test and radioallergosorbent test. However, allergic reactions do not play a decisive role in every case of AE. Other factors, such as nonspecific skin irritability or psychosomatic interactions, have to be considered. The concept of "extrinsic" versus "intrinsic" types of AE seems attractive. The concept of AE starting with TH2 inflammation, becoming TH1 inflammation in chronicity, and finally progressing to an autoimmune disease with IgE antibodies against autologous epidermal proteins is very attractive. Based on new knowledge, new methods in diagnosis, treatment, and prevention will develop, including more effective avoidance strategies, more potent anti-inflammatory treatment (e.g., immunomodulation or topical immunophyllins), and new ultraviolet modalities. The new findings have given rise to a possible new classification of eczema/dermatitis. The concept of "patient management," including all aspects from avoidance to therapy, has gained acceptance.