Allergy explained

Allergy is a malfunction of the immune system that causes a reaction to normally harmless substances called allergens. In this section, you will learn more about what triggers the reaction, the importance of IgE and why measuring IgE is an important step towards managing symptoms and helping patients feel better.

Allergic reaction  |  IgE |  Important to measure the IgE level  |  Mast cell  |  Histamine 

How is an allergic reaction triggered?

An allergic reaction is triggered by the particular substance (allergen) that a person is allergic to. When exposed to this allergen, the body senses a foreign invader.

The allergen binds to the IgE antibodies. When this happens, the mast cell breaks open to release inflammatory substances, e.g. histamine, which quickly travels through the body to fight off what it senses as harmful. The histamine affects the body tissue and causes an inflammation.

The symptoms that develop will depend on where in the body the histamine is released. Runny nose, itchy, watery eyes, shortness of breath and dry skin may all be sings of mast cells reacting in respective parts of the body.

For most people, allergy begins as a limiting and uncomfortable – but harmless – condition and it may be years before symptoms develop. For others, allergic reactions can be more serious and impose a threat to overall well-being. And in some rare cases, specific foods, drugs or an insect bite can result in sudden, life-threatening anaphylactic shock.

IgE – the body’s allergy antibodies

IgE - Imunoglobulin E - is a type of protein called an antibody. It plays an important role in allergy reactions and is therefore often called the “allergy antibody”.

If a person is allergic to a particular substance (allergen), the immune system mistakenly believes that this normally harmless substance, e.g. pollen, is in fact harmful to the body.

When the person exposed to this particular substance, the immune system starts the production of IgE as an attempt to protect the body. The IgE antibodies remain in the body and next time contact is made with the allergenic substance, an allergic reaction may occur.

As a result, a person who has an allergy has increased levels of IgE in his or her blood. IgE is specific to each allergen. That means that IgE to cat can only trigger an allergic reaction to cat.IgE.

Measure the level of IgE to learn what a patient is allergic to.

A blood test will help identify the amount of IgE in the body. Knowing a patient IgE levels for different substances will help identify the specific allergic triggers that may be contributing to your the symptoms, i.e. if the patient is allergic and to what.

Having a quantitative IgE test result will increase the possibility of ranking how different substances will affect the symptoms. A general rule of thumb is that the higher the IgE antibody value, the greater the likelihood of symptoms appearing. Allergens found at low levels that currently don’t result in symptoms can nevertheless help predict future symptom development.

The value of mast cells

Mast cells are an important part of the immune system and can be found throughout the body. Inside the mast cells are different chemicals, for example histamine, that cause inflammation.

The role of histamine in allergy

Allergy symptoms are caused by histamine that initiate an inflammatory response to protect the body. Histamine expands the blood vessels so that the mucous membrane will swell. It is released from the mast cells.

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.