Atopy and Atopic Disease

Atopic is a term used to describe an IgE-mediated response within the body following exposure to external irritants.

Most of us are acquainted with the term "allergy." We understand that it is an exaggerated body reaction to an external irritant. Allergies cover a broad range of reactions. Atopy, on the other hand, refers to a genetic predisposition to diseases in which IgE antibodies are produced in response to even limited exposure to environmental triggers that don't typically bother other people. Thus, all atopic reactions are allergies, but not all allergies involve atopic responses.

Often the two words are used interchangeably, although in clinical practice doctors are much more likely to use the word allergy. 

The following list contains the most common types of atopic disease:

• Allergic asthma
• Atopic dermatitis, also known as atopic eczema
• Allergic rhinitis (hay fever)

When a person who has an atopic disease is exposed to an allergen, an IgE response occurs that causes immune and blood cells to release substances, such as histamines, that trigger a variety of physical changes within the body. These changes can affect blood vessels, stimulate secretion of mucus, affect muscle functioning and create inflammation within cells of certain parts of the body.

With atopy, genetic factors are typically involved, although environmental factors appear to play a role in both onset and maintenance of symptoms.

As you will see, many of the triggers for atopy are air-borne:

• Animal dander
• Dust
• Dust mite droppings
• Mold
• Pollen

Symptoms may also be triggered by contact with certain chemicals, certain types of fabrics, and other environmental irritants.

As you will see, many of the symptoms of atopy are those that you would associate with an allergic reaction:

• Hives, welts, scaling or other signs of skin irritation
• Itching of the eyes, nose or skin
• Nasal congestion
• Redness of the eyes
• A runny nose
• Sinus pain and/or swelling
• Sneezing

The following symptoms indicate anaphylaxis which can be life-threatening and thus require immediate medical attention:

• Wheezing, shortness of breath or any difficulty breathing
• Rapid or slowed heartbeat
• Any signs of mental confusion or loss of consciousness

Some researchers have been exploring whether or not there is a connection between atopic disease and irritable bowel syndrome (IBS). This theory is based on the fact that mast cells associated with atopy, may also play a role in the onset and maintenance of IBS. Researchers are therefore exploring the possibility of an overlap between IBS and allergies. Some have gone so far as to coin the term "atopic IBS." You can be assured that as of now there is no known association between IBS and anaphylaxis risk.