What type of hypersensitivity reaction is characterized as immediate and IgE mediated?

The type of hypersensitivity reaction that is characterized as immediate and IgE mediated is indeed Type I hypersensitivity. This reaction typically occurs within minutes after exposure to an allergen, such as pollen, pet dander, or certain foods. The process involves the activation of B cells that produce IgE antibodies specific to the allergen. Upon re-exposure to the same allergen, these IgE antibodies bind to mast cells and basophils, leading to their degranulation and the release of various mediators such as histamine.

These mediators are primarily responsible for the clinical manifestations of immediate hypersensitivity, which can range from mild symptoms like allergic rhinitis or hives to severe reactions such as anaphylaxis. The rapid onset and the role of IgE in eliciting a strong immune response distinguish Type I hypersensitivity from the other types of hypersensitivity reactions.

Type II hypersensitivity involves IgG or IgM antibodies reacting with antigens on cell surfaces, leading to cell destruction, while Type III hypersensitivity is associated with the formation of immune complexes that can cause tissue damage. Type IV hypersensitivity, on the other hand, is a delayed-type reaction that involves T cells and does not require antibodies. This clear distinction in the immune mechanisms involved