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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.
IPEX (Immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome) is a syndrome caused by a genetic mutation in the FOXP3 gene, [2] [3] [4] which encodes a major transcription factor of regulatory T cells (Tregs). Such a mutation leads to dysfunctional Tregs and, as a result, autoimmune diseases.
Often, immunofluorescence microscopy can be used to visualize the immune complexes. [11] Skin response to hypersensitivity of this type is referred to as an Arthus reaction and is characterized by local erythema and some induration. Platelet aggregation, especially in microvasculature, can cause localized clot formation, leading to blotchy ...
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.
Immune complexes may themselves cause illness when they are deposited in organs, for example, in certain forms of vasculitis. This is the third form of hypersensitivity in the Gell-Coombs classification, called type III hypersensitivity. [4] Such hypersensitivity progressing to disease states produces the immune complex diseases.
Hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis (EAA) is a syndrome caused by the repetitive inhalation of antigens from the environment in susceptible or sensitized people. [ 1 ] [ 2 ] Common antigens include molds, bacteria, bird droppings, bird feathers, agricultural dusts, bioaerosols and chemicals from paints or plastics ...
The following outline is provided as an overview of and topical guide to immunology: . Immunology – study of all aspects of the immune system in all organisms. [1] It deals with the physiological functioning of the immune system in states of both health and disease; malfunctions of the immune system in immunological disorders (autoimmune diseases, hypersensitivities, immune deficiency ...