Fig. 1

The structure of the immunopathogenesis of allergic diseases. First, allergen-specific IgE and/or allergen-specific Th2 cell responses manifest through the sensitization phase. Thereafter, the clinical manifestations develop by allergy provocation through rechallenge with sensitized allergens. The classical pathway of immunopathogenesis of IgE-mediated allergy consists of allergen-IgE-FcεR1 binding on mast cells, followed by histamine release. Finally, histamine provokes allergic symptoms and signs, including urticaria, dyspnoea and even anaphylaxis. Additionally, there is an allergen-specific Th2 cell-mediated pathway that is important in eosinophilic inflammation in atopic dermatitis. Classically, many allergic diseases are allergen-specific. In chronic urticaria, autoimmune mechanisms play a role as an alternative pathway of immunopathogenesis and are not allergen-specific. Anaphylaxis due to drug allergies is a systemic disease, whereas allergic rhinitis and allergic conjunctivitis are generally limited to the nose and eyes. Allergic diseases present as local or systemic diseases