Immunoglobulins of type E (IgE) are one of several types of antibodies in our body. Standards for the amount of immunoglobulin E (IgE) have been established. If the results of the test show that the level of immunoglobulin E (IgE) is elevated, it may mean, inter alia, allergies. What else can too high levels of IgE antibodies prove? What role do they play in the body?
E-type immunoglobulins (IgE) , or E-type antibodies, are immune proteins produced by cells of the immune system - plasma cells, which are a type of B lymphocytes. IgE antibodies have been found in 1967 and were then called "reagins".
Like other antibodies, IgE is also made in the body when it comes into contact with various chemical molecules (antigens) that the immune system considers foreign. However, a special property of an IgE antibody is that it reacts with a specific group of antigens, i.e. allergens. Allergens activate their characteristic immune pathways, leading to the development of allergy symptoms.
Immunoglobulins type E (IgE) - total and specific
IgE antibodies can be divided into total and specific. Specific IgE antibodies are produced throughout life after contact with various antigens (allergens). The examination of specific IgE antibodies is important in the diagnosis of parasitic diseases and in the identification of substances causing allergies. All specific IgE antibodies in the body constitute the pool of total IgE antibodies.
Immunoglobulin type E (IgE) - role in the body
The concentration of IgE antibodies in the blood is low, only 0.00002-0.0005 mg / ml (0.002% of all antibodies). However, they are the only ones that can activate mast cells and basophils, cells that have granules inside them filled with biologically active substances, such as cytokines, histamine or prostaglandins.
Most mast cells are found in the mucosa of the respiratory and digestive systems, and the skin. On their surface there are receptors that recognize IgE antibodies. When mast cells and basophils are combined with IgE antibodies and an allergen, the content of granules is released and as a result of allergic symptoms, such as runny nose, sneezing, shortness of breath or diarrhea.
Immunoglobulin type E (IgE) - indications for the test
The indication for testing the level of immunoglobulin type E (IgE) is a suspicion:
- allergy
- parasitic diseases
- skin diseases, e.g. psoriasis
- lung diseases e.g. asthma
- leukemias, e.g. IgE myeloma
Immunoglobulin type E (IgE) - what is the test?
IgE antibodies can be tested in the blood, assessing their total concentration or allergen-specific. Total IgE is a screening test for the diagnosis of allergic diseases, and when elevated levels are found, specific IgE tests are performed to identify the allergen causing allergy symptoms.
Total IgE is most often tested using immunochemiluminescent methods. However, for the determination of specific IgE antibodies in the blood, methods based on radioactive isotopes, such as the RAST (radio-allergosorbent test) technique, were initially used. In the RAST method, the allergens are bound to a solid medium and after the addition of test material, e.g. serum, they react with specific IgE antibodies.
Then radiolabelled anti-human IgE antibodies are added and the signal read on a special detector. Currently, the RAST method has been replaced by methods in which the antibodies are labeled enzymatically (e.g. ELISA) or fluorescently (e.g. FEIA).
Immunoglobulins type E (IgE) - norms
The norm for the total concentration of IgE antibodies in the blood is dependent on age and gender (higher in males than in females). In addition, smokers have higher levels of IgE antibodies.
Norms for total IgE are:
- newborns: 5-10 U / ml
- children up to the age of 1: 30 units / ml
- children between 7 and 10 years old: about 300 units / ml
- adults: below 100 U / ml
Sample values for the semi-quantitative result for specific IgE:
- 0 - less than 0.5 kU / L
- 1 - 0.35-0.7 kU / L
- 2 - 0.7-3.5 kU / L
- 3 - 3.5-17.5 kU / L
- 4 - 17.5-50 kU / L
- 5 - 50-100 kU / L
- 6 - over 100 kU / L
Remember that the result must always be confronted with the standard values provided by a given laboratory.
Immunoglobulin type E (IgE) - results
The result of a specific IgE antibody test can be presented quantitatively (when the result indicates the exact concentration of antibodies, e.g. in U / ml, ng / ml or UI / ml), or semi-quantitatively, when the result is a scale (grades) from 0 to 5 (or 6 depending on the method used by the laboratory). The higher the class, the betterhigher concentration of IgE antibodies.
Immunoglobulin type E (IgE) - what does elevated level mean?
High levels of total IgE antibodies in the blood are most often associated with the presence of atopic diseases. Atopy is a hereditary tendency to over-produce IgE antibodies.
In some cases, even very high levels of IgE antibodies (over 500 U / ml) do not necessarily mean atopy, and normal values of total IgE do not exclude it either.
Therefore, the diagnosis should always be based on research and a detailed interview conducted by a doctor.
Increased levels of total IgE antibodies in the blood are observed in:
- allergic diseases, e.g. gastrointestinal diseases
- anaphylactic reactions caused e.g. by food, drugs, vaccines
- bronchial asthma
- lung diseases, e.g. bronchopulmonary aspergillosis
- parasitic invasions, e.g. celandine, pinworm, giardiasis
- bacterial infections, e.g. Helicobacter pylori, Mycobacterium tuberculosis
- viral infections, e.g. Epstein-Barr virus
- fungal infections
- skin diseases, e.g. psoriasis, alopecia areata, vitiligo
- cancers, e.g. IgE myeloma, chronic eosinophilic leukemia, lung cancer
- immunodeficiencies, e.g. Wiskott-Aldrich syndrome, hyperimmunoglobulinemia E (Job's syndrome)
- diseases of the gastrointestinal tract, e.g. celiac disease, ulcerative colitis
- vasculitis, e.g. Churg-Strauss syndrome, Kawasaki disease
- kidney diseases, e.g. nephrotic syndrome, drug-induced interstitial nephritis
High levels of specific IgE antibodies, e.g. against egg proteins, may indicate the presence of an IgE-dependent food allergy to chicken eggs.
Immunoglobulin type E (IgE) - what does low level mean?
Low IgE has virtually no clinical significance.
Bibliography:
- Nowicka U. Diseases and conditions with increased serum concentration of immunoglobulin E. Pneumonol. Allergol. Half. 2009, 77, 533-540.
- Laboratory diagnostics with elements of clinical biochemistry, a textbook for medical students edited by Dembińska-Kieć A. and Naskalski J.W., Elsevier Urban & Partner Wydawnictwo Wrocław 2009, 3rd edition
- Internal diseases, edited by Szczeklik A., Medycyna Praktyczna Kraków 2010
Karolina Karabin, MD, PhD, molecular biologist, laboratory diagnostician, Cambridge Diagnostics Polska FROMeducation - a biologist with a specialization in microbiology and a laboratory diagnostician with over 10 years of experience in laboratory work. A graduate of the College of Molecular Medicine and a member of the Polish Society of Human Genetics. Head of research grants at the Laboratory of Molecular Diagnostics at the Department of Hematology, Oncology and Internal Diseases of the Medical University of Warsaw. She defended the title of doctor of medical sciences in the field of medical biology at the 1st Faculty of Medicine of the Medical University of Warsaw. Author of many scientific and popular science works in the field of laboratory diagnostics, molecular biology and nutrition. On a daily basis, as a specialist in the field of laboratory diagnostics, he runs the content department at Cambridge Diagnostics Polska and cooperates with a team of nutritionists at the CD Dietary Clinic. He shares his practical knowledge on diagnostics and diet therapy of diseases with specialists at conferences, training sessions, and in magazines and websites. She is particularly interested in the influence of modern lifestyle on molecular processes in the body.