AND THE ANSWERS ARE . . . A majority of infants with AD will manifest respiratory allergies to aeroallergens. True The skin lesions of chronic AD contain large numbers of eosinophils. False The skin lesions of chronic AD contain large number of lymphocytes. True The serum IgE levels in children with AD is usually lower than seen in similar age children with respiratory allergies but no AD. False Food allergies play a pathogenic role in only a small minority of children with AD. False Comments There is a strong propensity to manifest IgE sensitivity to aeroallergens in a large majority of children with AD. The serum IgE levels in AD patients are often very high, particularly when the AD is chronically severe and extensive. These IgE levels are usually considerably higher than seen in children with respiratory allergies but no AD. Although eosinophils are usually frequent in acute AD skin lesions, whole eosinophils are usually quite sparse in chronic AD lesions. However, immunohistochemical studies have shown extensive extracellular deposition of eosinophil components such as major basic protein in chronic AD lesions, even when few if any whole eosinophils are seen. In contrast, lymphocytes are very frequent in chronic AD lesions. These are predominantly T lymphocytes expressing the Cutaneous Lymphocyte Antigen (CLA+), a surface agent which appears to direct accumulation of such lymphocytes into skin lesional areas in AD. Careful oral challenge studies have shown that food allergies play a pathogenic roles in at least 50% of cases of AD occurring in children. Also, special patch testing studies have convinced several investigative groups that IgE-mediated sensitivity to certain aeroallergens play a pathogenic role in some cases of AD. References 1. Allergy 2000 ;55:240-5 2. Pediatrics 2003;111:608-16 3. J Clin Invest. 2004;113:651-7 Please tell us what you think of this site. © Copyright 1997-2008 American Academy of Allergy, Asthma & Immunology All rights reserved