Dictionary of Allergies .. Atopy

The American researchers A.F. Coca and R.A. Cook reduced the concept of allergy to more manageable proportions when 1923 they proposed the term ‘‘atopy’’ for those clinical forms of allergy in which it was possible to demonstrate a common hereditary influence co-inciding eith the presence in the serum of special antibodies which they called regains, which today are the IgE antibodies.[1].

The term atopy, meaning strange disease, designates allergic conditions that are mediated by IgE antibodies. The reactions are always immediate, recur chronically, and if they take place in the skin, they are associated with an edematous, wheal-type skin reaction. The tendency to atopy and the susceptibility to react to specific antigens is both inhereted. Forrest etal. (1999) studied families with multiple cases of early onset AEDS for involvement of genes from the candidate regions on chromosomes 5q31 (IL gene cluster), 11q13 (high-affinity IgE receptor Fc RI), 14q11.2 (mast cell chymase), and 16p12 (IL-4 receptor -chain, IL4RA gene) [2]. A major locus that causes a general predisposition to atopy was found at 5q31; the authors postulated that this chromosomal region contains a gene predisposing to AEDS. Additionally, there are different genes that - combined with environmental factors - determine whether atopy manifests as eczema, asthma, or rhinitis.

The elsewhere reported linkage to 11q13 could not be supported by the findings of this study. The atopic diseases are processes mediated by or related to IgE-immediate hypersensitivity. The terms atopic and allergic are frequently interchanged. In its broadest sense, the term allergy has been used in the past to describe any immunologic alteration in the capacity to react following contact with foreign substance. Atopic on the other hand, characterizes conditions produced only by the action of IgE. (See Allergy).

References

1. Avenberg KM, Harper DS. Footnotes on Allergy. Pharmacia AB, 1980

Forrest S, Dunn K, Elliott K, et al. Identifying genes predisposing to atopic eczema. J Allergy Clin Immunol 1999;104: 1066-1070.