Inhaled or ingested allergens usually cause immediate hypersensitivity reactions.
The most common type of immediate hypersensitivity is type I hypersensitivity, also known as allergic reactions. This type of hypersensitivity involves the production of IgE antibodies in response to an allergen, which leads to the release of histamine and other mediators that cause symptoms such as itching, hives, and anaphylaxis.
An atopy is a hereditary disorder marked by the tendency to develop localized immediate hypersensitivity reactions to allergens.
Delayed hypersensitivity reactions, also known as type IV hypersensitivity reactions, are caused by T cells recognizing antigens and triggering an immune response. This can happen hours to days after exposure to the antigen. Common triggers include certain drugs, metals, and infectious agents.
A transfusion reaction is typically an acute hypersensitivity reaction to foreign red blood cells, which can occur immediately or within a few hours of the transfusion. Subacute hypersensitivity reactions usually take days to develop after exposure to the antigen, unlike the immediate onset of symptoms seen in transfusion reactions.
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IgE is the immunoglobulin associated with hypersensitivity reactions, such as allergies. When an allergen triggers the production of IgE antibodies, it can lead to a rapid immune response that causes symptoms like hives, itching, and even anaphylaxis.
Hypersensitivity refers to an exaggerated or inappropriate immune response to a substance, which can lead to tissue damage and various allergic reactions. It is classified into four types: Type I (immediate, such as allergies), Type II (cytotoxic, involving antibodies against cell surfaces), Type III (immune complex-mediated), and Type IV (delayed-type, involving T cells). Symptoms can range from mild reactions, like hives, to severe anaphylaxis. Proper diagnosis and management are essential to mitigate the effects of hypersensitivity reactions.
Hypersensitivity (also called hypersensitivity reaction) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. The four-group classification was expounded by P. H. G. Gell and Robin Coombs in 1963. (Wikipedia)
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Type I hypersensitivity reaction http://en.wikipedia.org/wiki/Asthma
not at alll there is a major diffrence trust me
Delayed hypersensitivity reactions-- Allergic reactions mediated by T cells that occur hours to days after exposure