IgE-mediated allergy in adults with severe atopic eczema


Professor R. StC. Barnetson, Department of Dermatology, University of Sydney, NSW 2006, Australia.


A study was carried out of 45 adults with atopic eczema sequentially admitted to the Dermatology wards in the Royal Infirmary, Edinburgh. The clinical course of the eczema, the associated atopic conditions and the possible role of inhalant and food allergens were assessed. Most subjects had developed eczema in early childhood, but nine of the 45 developed it for the first time after the age of 15 yr. Eleven subjects outgrew their eczema around puberty only to experience recrudescence in their late teens. In 18 subjects the eczema was flexural until the late teens, when it became widespread. In this group of severely affected subjects, 25 had a history of asthma, 29 had either seasonal or perennial rhinitis, and 10 had current symptoms of food allergy. All but one had elevated total serum IgE concentrations (range 63–50 000 kU/1). Using dilutions of the subjects' serum in the radio-allergosorbent test, an estimate of the specific IgE to 10 allergens (three inhalants, seven foods) was obtained, where 1 RAST unit is roughly equivalent to 1 IU total IgE. Most of the IgE was produced in response to the inhalant allergens tested (grass pollen, house dust mite and cat epithelium), 32 of the subjects having a RAST score of 3 or 4 to each of the three inhalant allergens, with the remaining 13 having a RAST score of 3 or 4 to at least one. The highest levels were to house dust mite, exceeding 1000 RAST units in 13 subjects. Thirteen subjects had a RAST score of 4 to at least one food allergen, with levels up to 1000 RAST units. Although this usually correlated with a history of allergy to the food (except in the case of wheat), some subjects with a positive RAST to a specific food could eat the food without problem. Overall these findings indicate that almost all subjects with severe atopic eczema have inhalant allergy, and produce high concentrations of IgE to inhalant allergens: roughly 25% of such subjects also have IgE-mediated food allergy, and they have high IgE concentrations to certain food allergens. The role of inhalant and food allergy in adult atopic eczema remains questionable, but should be considered in the overall management of the subject.