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 believed to be triggered by exposure to a substance. Allergic asthma is associated with high levels of immunoglobulin E (IgE), while non-allergic asthma is not.

IgE is an antibody that is naturally produced by B cell lymphocytes, a type of white blood cell, to help fight infection. IgE levels can also increase in response to exposure to an allergen, which is a harmless, non-infectious substance. IgE triggers a variety of allergic reactions that can manifest with a skin rash, sneezing, swollen lips, or asthma. Asthma caused by exposure to an allergen is called allergic asthma. 

Your levels may increase when you are exposed to allergens which cause you to rapidly produce excessive IgE antibodies that specifically bind to one type of substance. Common allergens include:

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

When your body releases IgE, this triggers a cascade of immune responses, 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, cause your airways to become narrow and inflamed, and exacerbate your asthma symptoms.

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

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

Because IgE may be elevated in allergic asthma, testing your IgE level with a blood test helps your doctor determine whether you will benefit from treatment to 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. IgE levels are more likely to be elevated in children with asthma since 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. You can also have an elevated IgE level with no identifiable cause.

Symptoms that suggest an allergic cause of your asthma include itchy eyes, nausea, sneezing, coughing, and congestion. 

An elevated IgE level supports the diagnosis of allergic asthma but does not give an indication of what the trigger, or triggers, of your attacks, could be. If you have not noticed an obvious cause and effect with respect to your asthma symptoms, you may need to undergo allergy testing to identify what may be triggering your condition.

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 for 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 when you are exposed to the triggering substance. The symptoms are usually mild, but they can be quite severe and may cause serious consequences. The condition is caused by an overreaction to a one or more specific allergens, and you are likely to have symptoms every time you are exposed to these allergens. 

If you are already on an allergic asthma treatment plan and are not controlled, speak with your doctor about revising your approach.