Immunoglobulin E (IgE) and Allergic Asthma

Asthma can be described as allergic or non-allergic. Allergic asthma, in which attacks are often triggered by exposure to a substance, is also called extrinsic asthma. Non-allergic asthma is often called intrinsic asthma, and episodes are not typically triggered by exposure to a substance.

Allergic asthma is associated with immunoglobulin E (IgE), while non-allergic asthma is not.

IgE is an antibody that is naturally produced by B cell lymphocytes, a type of immune white blood cell. This antibody normally activates physical responses to help your body fight infections.

For some people, exposure to allergens, which are harmless, non-infectious substances (like dust or pollen), can also trigger the body to produce and release IgE. In these situations, IgE antibodies bind to the allergen and trigger an inflammatory response that can manifest with allergy symptoms such as a skin rash, sneezing, swollen lips, or asthma. Asthma caused by exposure to an allergen is considered allergic asthma.

Common allergens include:

• Animal Dander
• Cockroaches
• Dust Mites
• Molds
• Pollen

When your body releases IgE, a cascade of immune responses follows, some of which are mediated by other immune cells in the body. IgE is believed to bind to and activate several types of immune cells, such as:

• Basophils
• Lymphocytes
• Mast cells

When IgE binds with any of these cells, it can overstimulate your immune system. Additionally, your capillaries widen and become leakier, increasing inflammation by allowing the immune cells to cluster around the allergen.

When you have allergic asthma, your bronchi (airways) can become narrow and inflamed due to the rush of immune cells—and this rapidly exacerbates your asthma symptoms. Not only do the inflammatory cells prevent air from passing through your airways, but your airways may also suddenly spasm, making it difficult for air to pass as you try to breathe.

Increased levels of IgE may contribute to symptoms of asthma, such as: 

• Wheezing
• Chest tightness
• Shortness of breath
• Chronic cough

Symptoms that suggest an allergic cause of your asthma include itchy eyes, nausea, sneezing, coughing, and congestion. Sometimes the pattern of symptoms can point to allergic asthma when symptoms tend to occur in relation to allergen exposure.

Diagnostic tests can be helpful. You may benefit from allergy testing to help identify what may be triggering your condition. And your doctor might test your IgE level to help determine whether you have intrinsic or extrinsic asthma.

Because IgE may be elevated in allergic asthma, testing your IgE level with a blood test helps your doctor determine whether you might benefit from treatment that can lower your IgE level. ​

If your IgE level is elevated, this does not necessarily mean that you have a diagnosis of asthma, but it does suggest that you may have some sort of allergic disorder.

Children who have asthma are more likely to have elevated IgE levels than adults with asthma. Asthma that begins for the first time during adulthood, called adult-onset asthma, is more likely to be intrinsic, non-allergic asthma.

Other conditions can also be associated with an elevated IgE level, such as an infection due to a parasite or an immune disorder. Allergic bronchopulmonary aspergillosis, a hypersensitivity to a soil fungus known as Aspergillus fumigatus, and Churg-Strauss syndrome, a type of vasculitis (inflammation of the blood vessels), are two uncommon causes of an elevated IgE level.

There are a number of treatments for allergic asthma, including avoiding allergens that are asthma triggers, if possible. However, it is not always possible to avoid allergens, especially if they are highly prevalent in the environment. Inhalers containing immunosuppressants or bronchodilators are commonly used to treat allergic asthma. 

Xolair (omalizumab) is an anti-IgE medication approved by the FDA for the treatment of allergic asthma for adults and children over the age of six. It binds to IgE antibodies to reduce their effects and help prevent (though not treat) allergic asthma attacks.

Xolair is given every two to four weeks as a subcutaneous (under the skin) injection administered by a healthcare provider. Side effects can include injection site reactions, infections, headaches, and sore throat.

Allergic asthma produces symptoms fairly quickly upon exposure to the triggering substance. The symptoms are usually mild, but they can be quite severe and may cause serious consequences, such as a life-threatening respiratory crisis.

The condition is caused by an overreaction to one or more specific allergens, and you are likely to experience symptoms every time you are exposed to these allergens. If you are already on an allergic asthma treatment plan without adequate control of your asthma, speak with your doctor about your persistent symptoms—you may benefit from revising your treatment approach.