Relationship between atopic dermatitis and immunoglobulin E.

Coca and Grove (1925) concluded that serum factors, which they called reagins, were present in individuals with allergic respiratory disease. More than 40 years later, reaginic antibody was shown by Johansson and Ichizaka to belong to the immunoglobin E (IgE) class of immunoglobins. It has been established that the Fc component of IgE has an affinity for surface receptors on mast cells and basophilic leukocytes. After IgE has become fixed to these receptors, binding of appropriate allergen to the Fab component of the immunoglobulin Initiates an inflammatory response via the release of pharmacologic mediators. IgE is not unique to individuals with atopic disease. Nearly all persons have detectable serum levels of IgE. Plasma cells in lymphoid tissue draining mucosal surfaces have been shown to stain with fluorescein-tagged anti-lgE, suggesting that IgE is produced in these areas. Like other immunoglobulins, IgE enters the bloodstream, but unlike the others, the quantity present shows extreme variability. IgE has been found at concentrations of less that 2.4 ng/ml in normal adult serum. Recently a nonmyeloma patient was discovered with a serum IgE level greater than 500,000 ng/ml. High IgE levels may be found 'in nonatopic individuals having several other conditions, including parasitic and fungal infections. It is difficult to establish a mean value for IgE levels in normal nonatopic individuals. There are no technical probFrom the Department of Dermatology, University of Michigan Medical School, Ann Arbor, Michigan