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What Is Immunoglobulin E (IgE)? - Definition, Function & Blood Test

What Is Immunoglobulin E (IgE)? - Definition, Function & Blood Test
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  • 0:00 Defining Immunoglobulin
  • 0:37 Immunoglobulin E
  • 1:25 IgE & Asthma
  • 2:48 IgE Blood Test
  • 3:40 Lesson Summary
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Lesson Transcript
Instructor: Hilary North

Hilary is a biomedical researcher with a PhD in neuroscience.

Brush up on how the immune system reacts to a pathogen, learn the role IgE plays in the process, and find out how IgE is being used to combat the rise in allergic reactions and asthma.

Definng Immunoglobulin

Feeling sick when you have a viral or bacterial infection is your body's way of killing the pathogen, but how does the body know when to react to the presence of an infectious particle? This is the job of the immune system, which utilizes antibodies to recognize pathogens and trigger responses to eradicate potentially harmful agents.

An antibody is a protein whose technical name is immunoglobulin. Said another way, immunoglobulins are particles circulating throughout your body keeping a watch out for infectious agents. There are just a handful of immunoglobulin types, and one of these is type E.

Immunoglobulin E

Immunoglobulin E (IgE) is a class of antibody that is specific to mammals; birds and fish do not have IgE in their immune systems the way humans do. Like all antibodies, it is a Y-shaped protein that contains binding regions for antigens, the foreign particles, on both arms of the Y. It comprises a very small percentage of the immunoglobulins found in mammalian blood: just 1 in 2,000 Ig proteins are IgE (less than 1%), compared to the nearly 3 of every 4 that are IgG, for example.

Immunoglobulin E (IgE) is responsible for conveying immunity to various parasites. However, it has gained attention recently due to its role in allergic reactions to stimuli, such as medicines, foods, and bee stings. It is also thought to be a cause of asthma.

IgE & Asthma

When the immune system encounters an environmental allergen and identifies it as dangerous or potentially harmful, it will deploy IgE to bind to the antigen, or infectious particle, such as pollen. The binding of the immunoglobulin to the antigen results in the inflammatory response, which is intended to rid the body of the infection or render it inert, but also causes the symptoms experienced by the affected person.

It is this process that causes a person to feel lousy while the body is fighting an infection: rising temperatures and mucous production are among the ways the immune system combats an intruder. In addition to taking these steps to fight the allergen, the immune system will also create more IgE molecules so that it can be better prepared the next time the same allergen presents itself.

If the immune system creates an overabundance of IgE, then the immune reaction to the next encounter with the allergen will be more effective but cause more discomfort to the individual. If the overabundance of IgE is higher than a healthy range, then the reaction to the allergen may cause more harm than the allergen would have in the first place.

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