Hypersensitivity types in 4 minutes

Hypersensitivity reactions When our immune system gets mad There are 4 types of hypersensitivity reactions, usually labelled in Latin numbers. In type 1, the antigen, which is usually external allergens such as pollens or certain food molecules, binds to IgE antibodies attached to the surface of mast cells or basophils. This antigen-antibody binding induces cascade of intracellular reactions resulted in release of large amount of histamine from the storage vesicles. The released histamine induces various degrees of allergic reactions. In hypersensitivity type 2, the antigen is not external allergen floating in the blood, but rather certain molecules attached to external surface of the patient cells. Binding of IgG or IgM antibodies stimulate cascade of immune reactions result in activations of complement system, natural killers, and macrophages. Which induce further damage to affected tissues. In hypersensitivity type 3 the small antigen-antibody complexes float thr