Immunoglobulin E (IgE)- Definition, Structure and Functions


Immunoglobulin E (IgE) is a type of antibody that belongs to the class of immunoglobulins, which are proteins produced by the immune system to fight against foreign substances such as bacteria, viruses, parasites and allergens. IgE is characterized by having an epsilon (ε) heavy chain, which distinguishes it from other classes of immunoglobulins such as IgA, IgD, IgG and IgM. IgE is present in very low concentrations in the blood serum, less than 1 microgram per milliliter (µg/mL), but it can bind to specific receptors on the surface of mast cells and basophils, which are types of white blood cells involved in inflammation and allergic reactions. When IgE binds to an antigen that it recognizes, it triggers the release of various chemical mediators from the mast cells and basophils, such as histamine, leukotrienes and cytokines, which cause the symptoms of allergic reactions such as itching, swelling, sneezing, wheezing and anaphylaxis. IgE also plays a role in immunity to certain parasites, especially helminths (worms), by coating them and facilitating their destruction by eosinophils, another type of white blood cell. IgE is produced by plasma cells, which are derived from B lymphocytes, in response to exposure to antigens. The production of IgE is regulated by several factors, such as genetic predisposition, environmental factors, infections and immunizations. The level of IgE in the blood can vary depending on the individual`s health status and exposure to allergens or parasites. High levels of IgE can indicate an allergic condition or a parasitic infection, while low levels of IgE can indicate a deficiency in the immune system or a rare genetic disorder called selective IgE deficiency.