Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease and often coexists with other atopic diseases, such as allergic rhinitis, conjunctivitis and asthma (Biedermann and Röcken 1999, Biedermann et al. 2001, 2004, 2006; Leung et al., 2000, 2003a, 2003b). Even though the immune pathology of AD is not precisely understood, today the new concept of atopic dermatitis pathology is based on a large set of data. In most patients with AD, dry skin and dysfunction of the epidermal barrier is found. As an important prove of concept, the loss of function mutation of the epidermal protein filaggrin impairing skin barrier function was found and can be detected in about 15% of kaukasian AD patients (Palmer et al., 2006). As a consequence, patients with AD are predisposed to develop sensitizations dominated by a Th2 immune phenotype (Hudson, 2006).