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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 an antigen. [ 1 ] [ 2 ] It is an abnormality in the immune system that causes immune diseases including allergies and autoimmunity .
In type I hypersensitivity, B cells are stimulated (by CD4 + T h 2 cells) to produce IgE antibodies specific to an antigen. The difference between a normal infectious immune response and a type 1 hypersensitivity response is that in type 1 hypersensitivity, the antibody is IgE instead of IgA, IgG, or IgM.
In the initial stages of allergy, a type I hypersensitivity reaction against an allergen encountered for the first time and presented by a professional antigen-presenting cell causes a response in a type of immune cell called a T H 2 lymphocyte, a subset of T cells that produce a cytokine called interleukin-4 (IL-4).
An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellular bacteria, protozoa, helminths, and fungi which could cause serious problems to the health of the host organism if not cleared from the body.
These diseases can come from one of the following problems. The first would be Hypersensitivity reactions, where there would be a stronger immune response than normal. There are four different types (type one, two, three and four), all with varying types and degrees of an immune response.
The adaptive immune system evolved in early vertebrates and allows for a stronger immune response as well as immunological memory, where each pathogen is "remembered" by a signature antigen. [55] The adaptive immune response is antigen-specific and requires the recognition of specific "non-self" antigens during a process called antigen ...
Immune responses can be inflammatory, and some of the worst foods for alopecia areata are those that trigger an inflammatory response. Other foods may affect hormone levels, so diet matters when ...
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.