Food Allergy in Atopic Dermatitis

Atopic dermatitis (AD) is a form of allergic skin inflammation characterized by late eczematous skin lesions [1]. These skin lesions occur through non-Immunoglobulin E (nonIgE)-mediated immune responses, and therefore, AD can be regarded as a non-IgE-mediated allergic inflammatory skin disease [2]. Many causes, including inhalant allergens, food allergens, and other factors, have been implicated in AD [1]. In addition to information about the causes, knowledge of the immunologic nature of AD is extremely important in order to understand AD. Without an understanding of the immunologic nature of AD, the cause of food allergy in patients with AD may be wrongly identified. Because of this confusion in establishing the cause of a food allergy in AD, the role of food allergy in AD remains poorly understood [2]. However, with the recent advance in the diagnosis and treatment of food allergy, it is necessary inevitably to distinguish between IgEand non-IgE-mediated food allergies that co-exist with AD in order to better understand and control AD [2]. It is well-known that food allergy is an important cause of atopic dermatitis [3]. Although food allergies can be either IgEor non-IgE-mediated, due to a lack of diagnostic modalities such as laboratory tests to diagnose non-IgE-mediated food allergy [4], it is difficult to clarify the nature of the food allergy, leading to confusion about role of food allergy in AD. Tests that determine IgE levels cannot predict the likelihood of an eczematous reaction because eczematous reactions are the result of non-IgE-mediated food allergies [2]. Until recently, discrimination of IgE-mediated and non-IgE-mediated food allergies was not considered necessary for diagnosis or treatment. Therapeutic modalities, including tolerance induction for food allergy (TIFA), have been developed for patients with food allergy [5,6]. However, the principles for diagnosing and treating IgE-mediated or non-IgE-mediated food allergies are quite different [7]. Presently, a differential diagnosis is absolutely necessary for relevant, proper, and successful treatment of IgE-mediated and non-IgEmediated food allergies, independently. Clinical approaches to treat food allergy in AD patients, including laboratory tests and diagnosis, should consider the conceptual differences between IgE-mediated and non-IgE-mediated food allergies. In the past, avoidance has been suggested as the main principle for treating food allergies [8]. More recently, however, the clinical and laboratory characteristics of IgE-mediated and non-IgE-mediated food allergy in atopic dermatitis have been well-characterized, and the