IgE Levels

Vertebrates have a powerful immune system that produces a number of antibodies in blood, when it detects harmful substances such as bacteria, virus, parasites, fungi and certain chemicals. These antibodies, also known as immunoglobulins (Ig), are used to neutralize the foreign objects that find entry into the body. They are produced by plasma cells and consist of heavy and light chains. Based on the type of heavy chains they possess immunoglobulins are grouped into different isotypes. In humans and other placental mammals, there are five antibody isotypes, namely, IgA, IgD, IgE, IgG and IgM. Each isotype has a different level of potency in the body.

Immunoglobulin E (IgE)

Immunoglobulin E is one of the five isotypes of antibodies which is found only in mammals. It was discovered in 1966, by the Japanese scientists Teruka and Kimishige Ishizaka. IgE plays an important role in conditions such as asthma and various allergies and is mostly associated with type 1 hypersensitivity. It is released by the immune system to fight against the foreign bodies and allergens that enter the body. Antibodies are generally found in the skin, lungs and mucus membranes of the body. They cause reactions as soon as they detect the presence of any environmental allergen such as pollen, fungus, spores or dander. These antibodies are tightly attached to the surface of mast cells through a high affinity receptor FcεRI. Like all other antibodies, This is specific to only one particular antigen. These antibodies raise an immune response by binding to Fc receptors that are present on the surface of basophils and mast cells. These receptors are also present on monocytes, eosinophils, macrophages and blood platelets. The presence of an allergen at any of these sites triggers the production of antibodies. The production of antibodies is generally controlled by environmental factors, however, it may also be influenced by genetic factors. If you are born with an immune system that produces low levels of antibodies, you may be at a higher risk of developing various infections.

Levels of IgE

The concentration of IgE is very low in the body as compared to other immunoglobulins. The normal levels are between 4.2 to 592 U/ml. A simple blood test can be done to determine the levels. People with allergies often have elevated IgE. Anything above 592 U/ml is considered as high concentration. High levels of IgE are generally seen in people with asthma, atopic dermatitis, certain types of cancer and autoimmune diseases, and a very rare disease called Job syndrome. Atopic individuals can have the levels raised up to 10 times the normal value. These people are more susceptible to allergic diseases such as asthma and hay fever. When the antibody detects an allergen, it has an interaction with its receptors and stimulates the release of chemicals such as histamines, leukotrienes and interleukins. These are the chemicals that cause many of the symptoms that we generally associate with allergy. Some examples of symptoms include airway constriction in asthma, increased secretion of mucus in allergic rhinitis and local inflammation in eczema. IgE levels below 4.2 U/ml are considered low and low levels of IgE are generally associated with rare immunodeficiency diseases. Low IgE can also occur as a sign of a rare inherited disease known as ataxia telangiectasia, which affects muscle coordination.

People with persistent asthma, who have not found relief with steroids or other therapies can benefit from an anti-IgE treatment known as Xolair, which blocks immunoglobulins. However, this option should be considered only after consulting your doctor as it involves several risks and dangers.