Atopy

Atopy (Greek ατοπία, ATOPIA, placelessness ') describes in medicine a tendency with hypersensitivity reactions, namely with allergic reactions of the immediate type (type I allergy ) to respond to the contact with otherwise harmless substances from the environment. So Atopy refers to a physical standby to a pathologically increased formation of immunoglobulin E antibodies (IgE).

Incorrectness of the term atopy is also used synonymously for allergies of the immediate type.

Causes

Atopy is an inherited and linked to the HLA system hypersensitivity. In addition to the allergens are also " Atopene " described that can activate the complement system and can release from mast cells by anaphylatoxins histamine, which here occur even in non- directly exposed parts of the body symptoms ( " placeless ," as opposed, for example, for Contact Dermatitis ).

The disease mechanism is not yet fully understood. Simplified one can speak of an excessive immune response, although ( inoffensive ) foreign antigens destroyed, but it also damages your own body. Probably it is an over fast after prior sensitization formation of specific antibodies of the IgE binding to mast cells and thus trigger their degranulation with distribution among them the Gewebshormons histamine, as well as to an increased complement sensitivity with formation of anaphylatoxin.

Atopic diseases develop but not only due to genetics. The environmental factors play a major role. Thus, a large study of more than one million respondents in 99 countries has shown that children who eat more fast food, more often suffer from atopic diseases. But It should be noted that the study can not prove a causal connection.

Clinical manifestations

Depending on the clinical appearance of this willingness to atopic reaction is referred to as

• Atopic eczema ( neurodermatitis), eczema, which differs by history, clinical features and so-called "associated characters " from the other forms of eczema,
• Allergic conjunctivitis,
• Hay fever,
• (exogenous allergic ) bronchial asthma,
• As allergic inflammation of the bowel or
• Rarely as urticaria.

In various degrees of severity affects up to 15 % of the population in atopic disorders.

Atopy stigmata

Certain physical characteristics - Stigmata - occur more frequently in people who show a predisposition to atopic reactions. These include:

• A double eyelid crease in the eyelid ( Dennie -Morgan fold )
• Dark skin around the eyes
• The thinning of the lateral eyebrows ( Hertoghe characters)
• Itchy, dry skin ( xerosis )
• Dry scalp
• Changes in the finger and toe crests ( pulpitis sicca)
• White dermographism
• Keratosis pilaris