Eczema, allergic rhinitis, asthma, food allergies... all these symptoms can be linked to what is known as an atopic condition. How is atopy defined? When was this disease identified? Let's delve into this.
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What is atopy?
Summary
- A bit of history on atopy in general
- Atopic dermatitis, the initial stage before the allergic disease
- Sources
Published February 16, 2024,
by
Maylis, Chemical Engineer
—
4 min read
Topics:
A bit of history on atopy in general.
The term "atopy" was introduced in 1923 by American allergists Coca and Cooke to denote certain hypersensitivity phenomena in humans. "Atopy" is derived from the Greek word "asopor" which means "out of place" or "strange disease". The allergists wanted to describe a hereditary tendency to be particularly sensitive to certain environmental substances such as dust, pollen, or food, and thus develop hypersensitivity reactions such as hay fever and asthma.
Subsequently, numerous population studies, particularly those conducted by Schwartz in Denmark and Schnyder in Switzerland, have confirmed the close association of bronchial asthma, hay fever, atopic dermatitis, and perennial rhinitis as classic atopic diseases. Today, the definition of atopy has somewhat evolved.
This is actually an exaggerated immune response associated with the presence of an allergen, leading to the production of IgE type antibodies (Immunoglobulin E). An atopic parent predisposes a child to a 25% chance of also being atopic, while this risk increases to 50% with two atopic parents.
Atopic dermatitis, the initial stage before the allergic disease.
Atopy is a predisposing factor for the development of allergic diseases such as asthma and food allergies. This is referred to as atopic march.
Atopic dermatitis, also known as atopic eczema, often initiates the atopic march. This atopy manifests as redness, dryness, and itching of the skin is caused by a dysfunction of the skin barrier (due to a lack of sebum, lipid, and cell adhesion molecule production) which can no longer perform its protective role. This dermatosis, very common in children (between 0.3% and 20.5% of children are affected), is often associated with allergic rhinitis, food allergies, and asthma attacks. Indeed, about 70% of children with severe atopic dermatitis will develop asthma during their lifetime. In comparison, 20 to 30% of children whose skin is minimally affected will develop this respiratory disorder.
In the majority of cases, atopic eczema disappears during childhood. However, in rare instances, it can persist into adulthood. The prevalence of atopic eczema has been increasing over the years. Environmental factors such as pollution or an increase in hygiene levels could explain this rise. Indeed, heightened hygiene during childhood could promote an atopic environment as the child is minimally exposed to pathogenic agents.
Note: The atopic march does not apply in all cases of allergic diseases. It is possible to develop asthma or a food allergy without previously exhibiting atopic dermatitis.
Sources:
Han, H., Roan, F. et Ziegler, S. F. The atopic march: current insights into skin barrier dysfunction and epithelial cell-derived cytokins. Immunological Reviews, (2017).
Zeng, T et al. The atopic march: progression from atopic dermatitis to allergic rhinitis and asthma. Allergy, Asthma and Immunological Research, (2011)
Gustafsson, D. Sjöberg, O. et Foucard, T. (2000). Development of allergies and asthma in infants and young children with atopic dermatitis – a prospective follow-up to 7-years of age. European Journal of Allergy and Clinical Immunology, (2000)
Tsakok, T. et al. Does a topic dermatitis cause food allergy? A systematic review. Journal of Allergy and Clinical Immunology, (2016)
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