IgE and Allergies: 5 facts you need to know
IgE and allergies are words that often are discussed hand-in hand. “IgE allergy” is a specific disease process and is NOT an intolerance. My previous blog post discussed food allergies compared to food intolerances. When doctors evaluate allergies, they frequently measure IgE; however, people do not know what IgE is!
Let’s start with some basics. “Ig” is an abbreviation for Immunoglobulins (Imm-YOU-no-GLOB-you-LINS). We do not pronounce “Ig” like we learned in school; we simply say the letters separately: I–G.
Immunoglobulins are antibodies made by our immune systems to fight foreign substances. Some of the things that our immunoglobulins (antibodies) attack include bacteria, viruses, fungus, animal dander, pollen, medications or cancer cells.
Antibodies react only to a specific foreign substance. For instance, antibodies for the flu virus do not fight the virus that causes chicken pox. We need immunoglobulins because if we do not make enough, we suffer from repeated infections.
We also make immunoglobulins (antibodies) which cause allergies, and sometimes we make antibodies that attack our own normal tissues. When this happens, an Autoimmune Disease occurs. Although most of our antibodies fight to keep our bodies strong, sometimes the antibodies we make lead to additional disease.
The 5 major classes of Immunoglobulins include:
- IgA: These antibodies, found on areas with a lining that produces mucous, protect surfaces of our body that are directly exposed to outside foreign substances. Examples include: ears, eyes, nose, throat, lungs, and stomach.
- IgG: These antibodies, found in all parts of our body, fight bacteria and viruses as well as other foreign substances on a daily basis. Although the smallest sized immunoglobulin, they represent 80% of the antibodies that we make.
- IgM: These antibodies, found in the blood and lymph fluid, respond to infections first and begin the process of protecting our bodies while other antibodies are being produced.
- IgE: These antibodies, found in the skin, lung and in areas with a lining that produces mucous, trigger the well known allergic reactions.
- IgD: Rarely talked about because it is not clear what they do!
So now you understand that IgE and allergies remain linked together because the Immunoglobulin E causes the allergic reactions.
5 facts you need to know about IgE and allergies:
1. Blood testing measures the amount of IgE in the blood
Traditional blood allergy testing measures amounts of IgE; however, people with no allergic disease show minimal amounts of IgE. This test serves as a marker that allergic disease is present, but should be combined with further history, examinations and testing for a more accurate diagnosis.
Some doctors measure the amounts of IgG, but this test fails to evaluate true allergy disease. IgE and allergies remain linked while IgG reactions represent an intolerance.
2. Skin testing measures the amount of IgE in the skin
The skin represents a major area for IgE to collect; therefore, one of the best ways to determine allergy severity includes performing skin prick testing. A small amount of the suspected allergen (food, pollen, dust, mold etc) is placed just under the skin while monitoring reactions. A red area around the site may develop, but the amount of swelling that occurs is most important.
3. Allergies run in families
Genetics plays a large role in developing allergies. For children, if only one parent has allergies of any type, a 25-40% chance exists that allergies will develop. If both parents have allergies, a 70-90% chance now exists that their children will have allergies. The specific allergy type is not passed on, just the likelihood of developing some type of allergy
4. The allergy reaction releases a chemical called histamine
Once IgE forms, it triggers a special series of steps leading to an allergic reaction. These immunoglobulins move through the body and interact with cells that release histamine. (HIS-tuh-MEEN).
Histamine is the chemical that causes many of the symptoms that we associate with allergies, so it makes sense why we treat our symptoms with medications that are called ANTI-histamines. We really need that histamine to stop doing the ugly things that lead to our allergy symptoms!
5. IgE is the root cause of common allergy diseases
This immunoglobulin plays a major role in the development of allergic asthma, allergic nasal disease, most types of sinusitis, food allergies, hives and chronic allergic skin rashes. It is also the key agent in developing severe reactions to medications and bee stings that require the use of an Epi-pen injection.
IgE and allergies represent the disease that many of us think about with true allergic disease. Although not exactly the same, feel free to use terms IgE and allergy interchangeably!