Introduction: Knowing your IgE is important if you have
allergic asthma, especially if you haven't been able to achieve complete control over
asthma symptoms yet. Each person has his own unique brand of asthma, with his own personal
asthma triggers and set of asthma symptoms. But 6 out of every 10 people who have asthma have a type of asthma known as allergic asthma.
When you have the allergic type of asthma, your body is thought to make too much of a natural substance known as Immunoglobulin E, or IgE for short, in response to certain
allergens, such as pollen, dust mites, pet dander and cockroaches. This extra IgE may lead to the development and persistence of airway inflammation, which results in asthma symptoms and
asthma attacks.
What It Is: IgE is a type of protein called an antibody. The body's
immune system produces antibodies in response to substances it perceives as threats to your health. In the case of asthma, the immune system produces the IgE antibody to combat allergens. Allergens are inhaled into the airways, including the nose, throat, and lungs, and attach themselves to the mucus membranes that line those organs. The immune system then sees these allergens as invaders and starts a process to fight them off.
What It Does: IgE role is to attach to the surface of allergen cells and certain immune cells in order to activate them. IgE is attracted to a specific kind of receptor on the cell. IgE is particularly attracted to the following kinds of immune cells:
All of these immune cells have large numbers of IgE receptors. When IgE interacts with allergens and then binds with the receptors on the immune cells, they release a variety of chemicals, such as histamine and leukotrienes, that act as messengers in stimulating acute bronchospasm in the airways. IgE also causes the release of other chemicals that prolong underlying airway inflammation.
IgE and the Immune Process: The immune process with allergies follows a 4-step reaction:
- You come into contact with asthma allergens such as animal dander, ragweed pollen or mold spores.
- Your body ramps up production of IgE, when then binds with the allergen you've had contact with.
- Several chemical reactions occur that eventually cause airway inflammation and swelling.
- You have asthma symptoms, such as wheezing and asthma attacks.
Why It Matters: Because IgE levels tend to be high when you have allergic asthma, then testing for those levels can help a doctor to make a diagnosis of asthma. The IgE test is a simple blood test that is much like those done for cholesterol or diabetes screenings. The IgE test can be done in as little as two minutes. However, it should only be performed and interpreted by an
asthma specialist, such as an allergist or pulmonologist.
Treatment Benefits: Research into a new type of asthma medicine called
immunomodulators, or IgE blockers, has helped experts realize there is value to reducing IgE levels in people who have allergic asthma. Because IgE is involved in the early stages of airway inflammation, experts believe that reducing IgE may help prevent asthma symptoms and asthma attacks before they start.
But also, experts now suspect that IgE is additionally involved in what is known as the allergic cascade. This happens when there is a second wave of inflammation and the allergic response 4 to 8 hours after the initial allergen contact was made. This produces a second round of allergy and asthma symptoms. This is called a late-phase reaction.
What You Can Do: Reducing your levels of IgE has been shown to be one of the keys to effective asthma treatment. So, it's crucial that you learn all you can about IgE and what level of IgE you have in your body. Getting your IgE test results can then help your doctor develop a better treatment plan for you, aimed at reducing your IgE level. If your IgE level falls between 30 and 700 IU/mL, then your doctor may decide to prescribe
Xolair injections for you.
Learn More:
Sources:
Genentech, Inc.. "IgE and Its Role in Asthma." . Genentech - In Business for Life. 21 Mar 2008.
Asthma & Allergy Foundation of America. "What's My IgE?." . AAFA. 21 Mar 2008.
Oettgen, Hans C., Geha, Raif S. "IgE in asthma and atopy: cellular and molecular connections." Journal of Clinical Investigation. 104/7: 1999. Available at: <http://www.jci.org/104/7/829?content_type=full
"Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma." NHLBI Guidelines for the Diagnosis and Treatment of Asthma. 28 Aug 2007. National Heart Lung and Blood Institute. 18 Dec. 2007 <http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf>
