reagins

Reagins are a class of antibodies, specifically IgE antibodies, that are involved in allergic reactions. These antibodies are produced by plasma cells in response to exposure to allergens, which are typically harmless substances like pollen, dust mites, or certain foods. Upon initial exposure, the immune system produces IgE antibodies that bind to mast cells and basophils.

During subsequent exposures to the same allergen, the allergen binds to the IgE antibodies on the surface of these cells. This binding triggers the release of potent inflammatory mediators, such as histamine, from the mast cells and basophils. These mediators cause the characteristic symptoms of an allergic reaction, including itching, swelling, hives, and difficulty breathing. The term "reagin" was historically used before the specific class of IgE was identified, referring to the substance in serum that could mediate immediate hypersensitivity reactions. While the term is less commonly used in modern immunology, it is still sometimes encountered.