Atopy

Atopy is the tendency to produce an exaggerated immunoglobulin E (IgE) immune response to otherwise harmless substances in the environment. Allergic diseases are clinical manifestations of such inappropriate, atopic responses.

Atopy may have a hereditary component, although contact with the allergen or irritant must occur before the hypersensitivity reaction can develop (characteristically after re-exposure). Maternal psychological trauma during pregnancy may also be a strong indicator for development of atopy.

The term atopy was coined by Arthur F. Coca and Robert Cooke in 1923 from the Greek ἀτοπία meaning "the state of being out of place", "absurdity". Many physicians and scientists use the term atopy for any reaction mediated by IgE (even those that are appropriate and proportional to the antigen), but many pediatricians reserve it to refer only to a genetically mediated predisposition to an excessive IgE reaction.