Immunoglobulin E, or IgE, is a protein found only in mammals. It is one of the proteins that are called antibodies, and they play a vital role in dealing with unwanted and dangerous foreign bodies in our system. Their purpose is to recognize the dangerous foreign bodies and help other components in our organism to fight them.
IgE is found in all humans, and they are located in the lungs, skin, and mucous membranes. They target foreign bodies such as pollen, fungus spores, and animal dander, and they help the body to react by detecting their presence. People with allergies tend to have a higher amount of IgE in their bodies.
The exact cause of eczema is still unknown, but it's believed that it has something to do with improper functioning of the immune system and genetically inherited skin sensitivity. It is a chronic condition characterized by red and dry skin that can become scaly and itch, and it sometimes appears along with allergic asthma or hay fever.
Eczema, allergic asthma, and hay fever are all atopic medical conditions, suggesting that they are a product of hypersensitivity to certain allergens.
When allergens enter the system of an atopic person, the immune system goes into overdrive and overreacts. This is enabled by a larger than normal amount of IgE in atopic persons. The high IgE count is more characteristic in patients with atopic dermatitis than in persons with other atopic conditions, which is why the levels of IgE in serum can be used as a diagnostic tool for atopic dermatitis.
Atopic dermatitis is a reaction mediated by IgE, but that doesn't mean that all the other types of dermatitis are also mediated by IgE. Contact dermatitis comes in two varieties: irritant contact dermatitis and allergic contact dermatitis.
Both of these forms look and feel the same as atopic dermatitis, but neither of them is mediated by IgE. Irritant contact dermatitis is caused by the irritating properties of the substance which came in contact with the skin. Allergic contact dermatitis on the other hand is a reaction to an allergen; however, it's not mediated by IgE.
Although atopic dermatitis is mediated by IgE, it would be wrong to say that IgE is the major factor in development of eczema. People can have other IgE mediated reactions - allergic asthma or hay fever - but still never develop eczema. The other factor is believed to have something to do with filaggrin, which is a protein that has a major role in the health and function of the outermost layer of the skin.
In the currently prevailing theories of the causes of atopic dermatitis, the inherited skin sensitivity would most probably have something to do with filaggrin, while the improper functioning of the immune system would have overproduction of immunoglobulin e as a consequence.
IgE certainly plays its part in mediating the reaction that manifests itself as eczema, but future research into causes of eczema might focus more on the other potential culprit.
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