When you have allergic asthma, your body is thought to make too much of a natural substance known as Immunoglobulin E (IgE) in response to certain allergens, such as pollen, dust mites, animal dander and cockroaches. This extra IgE may lead to the development and persistence of airway inflammation, which results in asthma symptoms and asthma attacks.
IgE's 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. 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.
Since IgE levels tend to be high when you have allergic asthma, then testing for those levels can help a doctor make a diagnosis of asthma. The IgE test is a simple blood test.
A new asthma medicine called Xolair is an immunomodulator, which is specifically designed to block the actions of IgE in order to control asthma symptoms. If your IgE level falls between 30 and 700 IU/mL, then your doctor may decide to prescribe Xolair injections for you.
