Atopy and allergy
Atopy is not yet an allergy – it can precede the onset of an allergy for many years. It is a permanent predisposition of the body to hypersensitivity to substances (e.g. allergens) to which people without this tendency do not react. It is an inalienable feature of the organism and cannot be ‘cured’ [2]. Atopy results in an overproduction of immunoglobulin E (IgE), antibodies that play a key role in the mechanism of the allergic reaction [1]. It is estimated that atopy affects up to 30% of the population in developed countries [2]. It can be diagnosed very early – as early as infancy. And in most cases, it is in children [3].
How can it be detected? The finding of an elevated IgE concentration in diagnostic tests (skin prick tests or blood tests) confirms sensitisation (atopy), but does not indicate allergy. We can only speak of an allergy when, in addition to a positive test result, we present symptoms after contact with the sensitising substance. In the case of sensitisation, symptoms of allergic disease can only be expected in the future (although they do not have to occur).
Is it a matter of genes? Atopy in children
Genetic factors play a significant role in atopy. Allergic diseases are not inherited, but the predisposition to them is. The full pattern of inheritance of allergy predisposition is complex – resulting from the interaction of many genes. Up to 80% of people with atopy have a family history of allergy [2]. Therefore, a thorough family history plays such an important role in diagnosis. However, it is important to remember that atopic diseases can also occur in people who have not inherited the genes implicated in the development of allergy [1]. This means that the risk of developing the disease always exists.
Interestingly, the study was able to test the association between the presence or absence of allergies in the parents and the likelihood that allergies will manifest in the child:
- no allergy in parents – risk of allergy in the child: 5-15%,
- allergy in one parent – risk of allergy in the child: 20-40%,
- allergy in both parents – risk of allergy in the child: 40-60%,
- same type of allergy in both parents – risk of allergy in the child: 50-80% [4,5,6].
Atopic diseases
Atopy – depending on the triggering factor – leads to the development of various types of allergies (inhalation, food, contact) in most affected individuals. These in turn may be associated with the occurrence of:
- bronchial asthma
- atopic dermatitis
- allergic rhinitis,
- allergic conjunctivitis,
- urticaria,
- angioedema,
- anaphylaxis [2].
Atopy has a multifaceted effect on health. This is demonstrated, for example, by studies conducted among the youngest children. Children with atopic diseases are less physically and socially active than healthy peers. They have poorer sleep quality, more absences from school, experience learning difficulties and higher levels of anxiety (this is especially true for children with food allergies) [3].
The prevalence of atopic diseases has been increasing in recent decades. Their prevalence varies from region to region. The more ‘western’ the lifestyle of a community (e.g. use of antibiotics, low-fibre diet, environmental pollution), the higher the prevalence. The development of atopy is favoured by increasing urbanisation [3].
On the other hand, there is increasing evidence that a balanced gut microbiome (i.e. the total number of organisms inhabiting the gut), which is most intensively formed by the child’s second year of life, may protect against atopic diseases [7].
What is the atopic march?
Atopy is a lifelong and evolving problem. Relevant in this context is the phenomenon of the so-called atopic march, characterised by the transition of one atopic disease to another. It is assumed that the atopic march leads from food allergy through AD to bronchial asthma [8]. However, it does not always proceed in the same way [3]. In some, it may start with atopic dermatitis, then progress to asthma and finally to allergic rhinitis [3].
Both the symptoms and the pool of allergens to which a patient is allergic vary [8]. In general, a person with atopy begins to tolerate food allergens better with age, but tolerates airborne allergens less and less well. Most children develop tolerance to foods several months after the introduction of an elimination diet [8]. However, this is usually not the end of their journey through atopic disease.
