Final answer:
The process where an individual is exposed to an allergen and becomes prone to an allergic reaction is called sensitization. This leads to type I hypersensitivity, which can result in various allergy symptoms. Desensitization therapy is a treatment that aims to diminish the hypersensitivity by exposing the patient to small amounts of the allergen over time.
Step-by-step explanation:
Understanding Allergic Reactions and Sensitization
In the context of allergic reactions, the process by which patients must be exposed to an allergen at some point to develop an allergy is called sensitization. This is a prerequisite for what is known as type I hypersensitivity, where a sensitized individual has an immediate immune response upon subsequent exposure to the allergen. This immune reaction is mediated by IgE antibodies that, upon the first exposure, sensitize the mast cells. Then, during later exposures, these IgE antibodies trigger the mast cells to release histamine and other inflammatory chemicals, leading to allergy symptoms ranging from mild to severe, including life-threatening anaphylaxis.
Desensitization therapy, on the other hand, is a treatment method aimed at reducing hypersensitivity reactions through repeated injections of allergens in very dilute concentrations. This technique can eventually lead to the production of allergen-specific IgG antibodies that act as blocking antibodies to neutralize the allergen before it can bind to IgE on mast cells, thereby preventing the allergic reaction from occurring.