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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.
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.
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.
An autoimmune disease is a condition arising from an abnormal immune response to a normal body part. [5] There are at least 80 types of autoimmune diseases. [5] Nearly any body part can be involved. Common symptoms include low-grade fever and feeling tired. [5] Often symptoms come and go. [5]
Atopy is the tendency to produce an exaggerated immunoglobulin E (IgE) immune response to otherwise harmless substances in the environment. [2] Allergic diseases are clinical manifestations of such inappropriate, atopic responses.
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 ...