What are the functions of immunoglobulin E (IgE)?

Functions of Immunoglobulin E (IgE)

• IgE primarily protects against helminth parasites and responds to foreign substances even in small amounts, acting as a gatekeeper.
• It is predominantly associated with allergic reactions and is particularly significant in responses to allergens such as bee stings, anaphylactic drugs, and antigen preparations used in desensitization immunotherapy. It acts as a mediator in allergic reactions of Type I by interacting with antigens and receptor molecules on the membrane of tissue mast cells and blood basophils in the human body.  
• High levels of IgE can indicate overreaction to allergens and can be a sign of certain immune system conditions or the body fighting a parasitic infection. 
• Antigen-induced cross-linking of receptor-bound IgE triggers the release of histamine and heparin, increasing vascular permeability and promoting smooth muscle contraction.
• IgE mediates mechanisms that facilitate degranulation of mast cells and basophils, promoting TH2 immunity. These mechanisms are involved in defending against toxins, parasitic worms, venoms, environmental irritants, and noxious substances. They are also responsible for triggering allergic reactions in individuals with allergies.  
• It serves a key role in type I hypersensitivity, which manifests as various allergies including mot types of sinusitis, allergic asthma, some types of atopic dermatitis, allergic rhinitis, and chronic urticaria.   
• Plays an important role in defending against parasites such as Trichinella spiralis, Fasciola hepatica, and Schistosoma mansoni, and Plasmodium falciparum.
• Although the exact mechanisms are still unclear, IgE appears to play a role in repelling ticks of the Ixodid family, which are carriers of diseases such as ehrlichiosis and Lyme disease.