Mechanisms of Processes Which Make the Organism Hypersensibilized and Type I Hypersensitive Reaction

A hypersensitivity reaction is an altered immunologic response to an antigen that results in disease or damage to the individual. Hypersensitivity reactions can be classified in two ways: by the immunologic mechanism that causes disease (types I, II, II, and IV), and by the source of the antigen that the immune system is attacking (allergy, autoimmunity, and alloimmunity (also termed isoimmunity). The mechanism that initiates the onset of hypersensitivity reactions is not completely understood. It is generally accepted that genetic, infectious, and environmental agents are contributing factors.