About 50 years ago, the discovery of IgE marked a new era in immunology. This antibody shields you against parasites and cancer, but it also triggers intense allergic reactions. Learn what this lab marker can tell you about your health and how to keep it in check.
What Is IgE?
Immunoglobulin E (IgE) is a type of antibody. Our immune cells called B cells (or plasma cells when activated) produce antibodies in response to allergens, pathogens, cancer cells, and other threats. Antibodies help our immune cells recognize and remove these “intruders” [1, 2].
Scientists assume that IgE flags all kinds of unwanted components, acting as the “gatekeeper” of our immune system. In response to these components, T immune cells release the cytokines IL-4 and IL-13, which stimulate the production of IgE antibodies [5, 6].
Source: Wright et al., 2015
IgE mediates the most common allergic reaction, known as type 1 hypersensitivity. This is an uncontrolled immune response to components in the environment (antigens) in allergic diseases such as :
- Atopic dermatitis (eczema)
- Allergic rhinitis (hay fever)
- Food allergies
An allergic person produces specific IgE antibodies to an allergen during the first contact, known as sensitization. These antibodies bind to immune cells (mast cells and basophils), enabling them to recognize the allergen next time .
Next time the same allergen reaches the body, massive amounts of IgE stimulate mast cells and basophils to release histamine and other “defense weapons.” This results in unpleasant symptoms ranging from skin itching to life-threatening conditions [9, 10].
Our B cells produce a specific type of IgE for each allergen, and that’s why you can be allergic to only one thing, such as peanuts, or a couple of them .
This antibody evolved as our defense mechanism against parasitic infections. The presence of parasites (helminths) in your body triggers vigorous IgE production .
The resulting chain reaction also involves mast cells, and it’s meant to destroy and remove the intruder. But this time, the threat is real, the response is fine-tuned, and it helps us stay healthy.
Emerging evidence voices the importance of these antibodies in cancer prevention. They flag cancer cells and help our immune system remove them before they start spreading .
Indeed, higher levels of IgE may protect you against some types of cancer (more details below).
IgG vs. IgE
IgG immunoglobulins are our main antibodies, accounting for approximately 75% of the total amount. They shield us from infections by flagging all kinds of pathogens, such as bacteria, viruses, and fungi .
On the other hand, IgE is present in tiny amounts under normal conditions, and it’s specialized for parasitic infections.
IgG antibodies can also be anti-inflammatory and indicate tolerance (not sensitivity!) to specific foods. That’s why IgG-based food sensitivity tests don’t work .
IgE Blood Test
You usually get an IgE blood test when you have recurring infections or to monitor immune disorders such as allergies.
New methods, such as ImmunoCAP (based on fluorescence), have been replacing the standard one called RAST (based on radioactive tracking).
These new methods are more sensitive and, besides total IgE levels, they also detect and measure specific IgE antibodies with up to 98% accuracy. This feature can aid in the diagnosis and management of allergies .
On the other hand, total IgE is not a specific marker and can’t be used to diagnose a particular disease. It can, however, reveal certain clues, such as the risk of allergies, infections, and some chronic diseases .
Normal IgE Levels
IgE has the lowest concentration of all antibodies, especially in people without allergies. Normal values may vary in the scientific literature, but the usual reference range is 1.5-144 kU/L (IU/mL) [1, 23].
- Alcohol consumption
- Environmental factors
- Immune status
We’ll dive into details about each one below.
In summary, different factors can influence immunoglobulin E levels, but most healthy adults will be in the range of 2-150 kU/L.
High IgE levels
Allergies are the most common cause of elevated IgE. IgE increases in response to allergens, which are different for each person. For some, the triggers are dietary (food allergies), and for others they are seasonal (pollen allergies) .
Eczema, Asthma, and Hay Fever
Atopic dermatitis or eczema generally causes the highest IgE levels, followed by asthma and hay fever. In a study on Chinese children, those with higher IgE also had more severe forms of eczema. In people with seasonal allergies, levels peak 4-6 weeks after pollen season [28, 36].
In over 1K people, those without allergies had the lowest average values (43.7 kU/L), followed by people with hidden allergies (213.8 kU/L) and asthma (626.6 kU/L) .
Hidden allergies are not accompanied by the typical symptoms. Apparently, even slightly elevated IgE might point to them.
A study on 562 children confirmed the connection between asthma and total IgE levels. It was a useful marker of lung sensitivity even in symptom-free children .
In 69 people with chronic hay fever, the average IgE levels were 378 kU/L – well above the normal range .
Exposure to food allergens induces only a short-term increase in total IgE. It’s interesting that processed foods containing a particular allergen may cause 3-8 times higher levels compared with raw food allergens [32, 39].
Total IgE can’t detect food allergies, but tests that measure specific antibodies might do so .
Both an allergic predisposition and full-blown allergies are common causes of high IgE levels. The greater the exposure to the allergen, the more IgE will increase.
The use of total IgE for allergy diagnosis comes with notable limitations we’ll discuss below (see “Limitations and Caveats”).
2) Parasitic Infections
As mentioned, the primary role of IgE is to detect and help eliminate worms and other parasites from our bodies. In the absence of allergic tendencies and symptoms, parasitic infection is the most probable cause of high IgE [41, 42].
We produce some parasite-specific IgE immunoglobulins, but they aren’t always detectable in people with infections. Additional tests from a feces sample or blood smear may be necessary to confirm the diagnosis [43, 44].
3) Th2 Dominance
4) Race and Location
5) Rare Diseases
Hyper IgE syndromes (HIES) are rare disorders accompanied by high blood IgE. People suffering from them experience frequent skin and respiratory infections due to impaired immunity .
Job’s syndrome is the most common type which causes a range of bone and connective tissue abnormalities. IgE levels reach up to 2,000 kU/L, but they can drop (and even normalize) in adulthood .
Both conditions are uncommon, and there’s no reason to panic if your blood test revealed high IgE levels. A benign cause, such as allergen exposure is much more probable.
According to a study on 877 Korean asthmatics, mutations (SNPs) in the following genes might increase total IgE levels :
Other conditions or lifestyle factors that may elevate IgE include:
- Smoking [23, 27, 26]
- Alcohol consumption [31, 53, 54]
- Inflammatory bowel disease (IBD) [55, 56]
- Bacterial and viral infections [57, 28, 58]
- Lymphomas (lymphatic system cancers) [59, 56]
- Nephrotic syndrome (kidney disorder) [60, 61, 62]
- Itchy skin and eyes
- Coughing and sneezing
- Difficulty breathing
- Low blood pressure
- Sudden weight loss
- Digestive issues
However, type 2 diabetic patients had lower IgE levels compared with controls (22.5 vs. 43.3 kU/L) in a Japanese study while the average for type 1 diabetics was slightly higher (56.7 kU/L) .
Although it usually signals an undesirable event, high IgE might actually protect you against some types of cancer.
A meta-analysis of 8 clinical trials (over 6K people) found a 27% reduced risk of brain tumors in people with high total IgE .
According to a comprehensive study on almost 38K individuals, elevated IgE has mixed effects on different types of cancer. After removing other factors, higher IgE predicted up to 56% lower risk of blood cancers .
IgE antibodies can help your immune system target and destroy cancer cells. New IgE-based cancer drugs have shown promising results in test tubes and animal trials. This kind of research belongs to a growing field of medicine called AllergoOncology [76, 14].
How to Reduce IgE Levels
1) Avoid Allergen Exposure
If you are allergic to a particular food or animal, avoiding them will help prevent allergic reactions. You may also want to clean your house and workspace regularly to get rid of dust mites or mold.
2) Increase Your Vitamin E Intake
- Sunflower seeds
3) Refrain From Smoking and Alcohol Consumption
4) Consider Taking Supplements
Besides probiotics, the following supplements may combat IgE overproduction:
Most studies have examined the effects on allergic responses, and it’s not clear whether these supplements can help reduce high IgE due to other causes.
5) Drug Treatment
Your doctor may prescribe immune-stabilizing drugs to manage your high IgE levels. Treatment will depend on the underlying disease and your overall symptoms.
For example, you may get an inhaled medication for asthma, creams for eczema, or nose sprays for hay fever.
These drugs may contain corticosteroids (to reduce swelling), antihistamines (to block histamine-triggered inflammation), or decongestants (to relieve nose stuffiness) .
Additionally, some IgE-targeted drugs include:
- Omalizumab, a biological drug that contains anti-IgE antibodies. These bind to IgE and remove it from the bloodstream, thus reducing allergic response. The FDA approved this drug for severe asthma and chronic hives (urticaria) [93, 94].
- Nedocromil sodium and disodium cromoglycate (cromolyn sodium), which belong to a group of drugs called mast cell stabilizers. They are available as inhalers, nasal sprays, and eye drops for asthma and seasonal allergies [95, 96, 97].
Low IgE Levels
Causes and Symptoms
IgE levels can be quite low in the absence of the above conditions, and this usually doesn’t indicate any disorder.
Selective IgE deficiency (IgE hypogammaglobulinemia) is a type of immunodeficiency with the levels of this antibody below the limit of detection: <2-2.5 kU/L. It may cause the following symptoms [98, 25]:
- Joint pain
- Chronic fatigue
- Difficulty breathing
If the levels of other antibodies (IgG, IgM, IgA) are low, common variable immunodeficiency (CVID) is the most probable cause. People with CVID have frequent respiratory and other infections that may lead to tissue damage [99, 100, 101].
- Drug treatment
- Kidney and gut disorders
- Severe burns
IgE is low in such cases but usually above 2 kU/L .
Although autoimmunity and immunodeficiency may seem like opposite conditions, they are actually “two sides of the same coin” .
In a study with over 1K people, those with IgE deficiency had an increased risk of :
- High blood pressure, 2-fold
- Heart disease, 3-fold
- Stroke, 6-fold
As mentioned above, high IgE may raise the risk of cataracts in the elderly. Same goes for low levels as those with ≤35 kU/L had a 67% higher risk .
Being unspecific, the cost-effectiveness and the routine clinical use of total IgE blood tests is questionable .
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Immunoglobulin E (IgE) is an antibody that fights parasitic infections, microbes, and cancer cells. It is also involved in allergic reactions. This makes allergies and parasitic infections the two most common causes of high total IgE (>150 kU/L). High IgE may increase your risk of cataracts and diabetes, but it may protect you against brain and blood cancer.
To lower your IgE naturally, increase vitamin E intake and refrain from smoking and alcohol consumption. Consider supplementing with probiotics, fish oil, and flavonoids.
Low or undetectable IgE (<2-2.5 kU/L) usually points to an immunodeficiency disorder that can cause frequent infections, gut disorders, and autoimmune diseases.