Compare and contrast type I hypersensitivity with type IV hypersensitivity with

Type I (immediate) hypersensitivity is very quick. The reaction time can be seconds to minutes after exposure to the allergen. This type of hypersensitivity starts with a prior sensitization to the allergen where IgE is produced specific for the allergen. The IgE that is made binds to mast cells, basophils, and eosinophils. The anaphylaxis can be either local or systemic and is due to a subsequent exposure to the allergen. Upon subsequent exposure, the allergen binds to the IgE on mast cells, basophils, and eosinophils, causing them to degranulate and release a variety of inflammatory molecules, including histamines, kinins, proteases, leukotrienes, and prostaglandins. Type IV (delayed or cell-mediated) hypersensitivity has a much slower reaction time. It takes 12—24 hours to start developing. Antigen does not bind to antibody; it binds to antigen-presenting cells and T cells. As with type I, the reaction is due to a prior exposure, but in the case of type IV, memory T cells are produced. In both type I and type IV, inflammation is a common result.