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Hypersensitivity (also called hypersensitivity reaction or intolerance) is an abnormal physiological condition in which there is an undesirable and adverse immune response to antigen. [1] [2] It is an abnormality in the immune system that causes immune diseases including allergies and autoimmunity .
Immunology. Type I hypersensitivity (or immediate hypersensitivity ), in the Gell and Coombs classification of allergic reactions, is an allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen. [1] Type I is distinct from type II, type III and type IV hypersensitivities.
Common [10] Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. [11] These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. [1]
Type III hypersensitivity, in the Gell and Coombs classification of allergic reactions, occurs when there is accumulation of immune complexes ( antigen - antibody complexes) that have not been adequately cleared by innate immune cells, giving rise to an inflammatory response and attraction of leukocytes. There are three steps that lead to this ...
Type IV hypersensitivity, in the Gell and Coombs classification of allergic reactions, often called delayed-type hypersensitivity, is a type of hypersensitivity reaction that can take a day or more to develop. [1] Unlike the other types, it is not humoral (not antibody -mediated) but rather is a type of cell-mediated response.
Type II hypersensitivity, in the Gell and Coombs classification of allergic reactions, is an antibody mediated process in which IgG and IgM antibodies are directed against antigens on cells (such as circulating red blood cells) or extracellular material (such as basement membrane). This subsequently leads to cell lysis, tissue damage or loss of ...
A patch test (contact delayed hypersensitivity allergy test) is a commonly used examination to determine the exact cause of an allergic contact dermatitis. According to the American Academy of Allergy, Asthma, and Immunology, "patch testing is the gold standard for contact allergen identification".
Specialty. Gastroenterology, immunology. Food intolerance is a detrimental reaction, often delayed, to a food, beverage, food additive, or compound found in foods that produces symptoms in one or more body organs and systems, but generally refers to reactions other than food allergy. Food hypersensitivity is used to refer broadly to both food ...
Frequency. ~6% (developed world) [1] [2] A food allergy is an abnormal immune response to food. The symptoms of the allergic reaction may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure. This typically occurs within minutes to several hours of ...
The Arthus reaction involves the in situ formation of antigen/antibody complexes after the intradermal injection of an antigen. If the individual has circulating antibody either from passive immunity or because of prior encounter with the antigen, an Arthus reaction may occur. Typical of most mechanisms of the type III hypersensitivity, Arthus ...