What is IgE?

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  • Written By: Karyn Maier
  • Edited By: Bronwyn Harris
  • Last Modified Date: 21 August 2019
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IgE stands for immunoglobulin E, and is one of five types of immunoglobulins involved in immune sensitivity and response in humans. However, IgE is found exclusively in mammals. Immunoglobulins, more commonly known as antibodies, also belong to a family of proteins referred to as gamma globulins. They are produced by specific white blood cells called B-lymphocytes. Collectively, IgEs, which reside in the blood, are important weapons used by the immune system to detect and respond to the invasion of foreign substances, namely bacteria and viruses.

As might be expected, IgE is also involved in allergy hypersensitivity and allergic reactions. In fact, IgE is the primary mediator that stimulates the release of inflammatory agents in mast cells, such as histamine and leukotrienes. In addition, it is responsible for triggering the most severe allergic reactions, even though it is usually the immunoglobin found least in circulation in the blood. In addition, there is sufficient evidence to suggest that IgE is involved in immune responses to parasitic invasions and the increased white blood cell count associated with the onset of cancer.


The role of IgE is to target and bind to a particular protein found on the surface of certain cells, such as mast cells, macrophages, and natural killer (NK) cells. These proteins are referred to as Fc receptors and are further classified depending on the specific antibody that they bond with. Receptors that differentiate IgE specifically are called Fc-epsilon receptors (FcεR). The result of their bonding together is the release of inflammatory mediators (i.e., histamine) that produce inflammation in smooth muscles and increase mucous secretions.

While IgE is involved in skin allergies resulting from direct contact with an allergen, it is also involved in atopic reactions, indicating hypersensitivity without direct contact. In fact, excessively high serum levels of IgE antibodies usually accompany inflammatory conditions like eczema. However, in terms of asthma, which is also an inflammatory disease, the predictable allergic response may occur even though blood concentrations of IgE antibodies are relatively low. This is because once an allergic reaction has been initiated, the protein receptors become “primed,” or programmed to recognize the same allergen when introduced and respond in the same way as before.

The typical treatment of IgE-induced allergy is treatment with medications such as antihistamines. While the name implies that the production of histamine is hindered, what actually occurs is histamine being blocked from release at receptor cites. However, new drugs are being developed with the aim to prohibit IgE from binding to these receptor sites in the first place.


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Post 3

I had IgE allergy testing done last week and found out that I'm allergic to a bunch of stuff!

My doctor said that my IgE levels were too high, far above normal which means that I'm allergic to something.

I now have a long list of foods to avoid, most of them are nuts, fruit, and herbs. I'm kind of upset that I have to look at the list before I eat out now but it's good to know too.

I used to have terrible bloating and unexplained skin rashes earlier and they've all disappeared. It turns out it was food allergies!

Post 2

@burcinc-- It's true that IgG, IgM, and IgA deficiencies are more common than IgE deficiencies.

As far as I know IgE deficiencies are often seen in people with Common Variable Immune Deficiency (CVID). In this disorder, there is a deficiency in almost all immunoglobulin types, often including IgE.

And it's not true that those with an IgE deficiency don't take antibiotics, they may have to if they have infections often.

IgE deficiency is dangerous if the levels are really low or nonexistent. IgE causes reactions in our body when there is an allergen. IgE deficiency prevents this reaction so we have no warning mechanism so to speak. People can easily go into anaphalactic shock if they are unaware that they're having an allergic reaction which is the case with serious IgE deficiencies.

Post 1
How common is IgE deficiency? I don't think it's very common, right?

I have a cousin with Celiac disease and she has IgA and IgG deficiency. I think these two are seen pretty often because of genetic conditions or certain serious disorders but I've never heard of IgE deficiency before.

IgE deficiency does sound a lot better than IgA and IgG deficiency though. My cousin has to take antibiotics all the time because she's so prone to infections. At least with IgE deficiency, antihistamine medications are enough.

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