[The atopy syndrome].

Atopy is defined as that familial form of increased reactivity which is characterized by a probably genetically determined, spontaneously occurring preferential production of IgE as a response to the natural exposure to allergens normally present in the environment, and whose clinical manifestation as a disease is additionally dependent on a non-immunologically conditioned increase in reagibility of the tissues. An attempt is made to show how many different factors must cooperate to produce atopic disease, and how these factors are mutually influenced by their actions. The implications of this definition of atopy are discussed with reference to prophylaxis and treatment in clinical practice.