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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.
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 .
Arthus reactions (type III hypersensitivity reactions) are rarely reported after vaccination and can occur after tetanus toxoid–containing or diphtheria toxoid–containing vaccines. An Arthus reaction is a local vasculitis associated with deposition of immune complexes and activation of complement.
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 ...
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.
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.
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.
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 ...