Hypersensitivity Reactions in the Respiratory Tract

Chemicals and proteins can cause hypersensitivity reactions in the respiratory tract via multiple mechanisms. Hypersensitivity responses require a latent period and develop in two stages: An induction or sensitization phase and an elicitation or effector phase with appearance of symptoms. Often, the hypersensitivity reaction to a given allergen involves a combination of both humoral (Types I-III) and cell mediated (Type IV) components leading to disease. This chapter will focus on hypersensitivity reactions in the respiratory tract that are most often encountered by toxicologists including allergic rhinitis, allergic asthma, anaphylaxis, and hypersensitivity pneumonitis. In addition, chronic beryllium disease will be presented as an example of a Th1-mediated hypersensitivity reaction. Current knowledge of mechanisms will be presented as well as animal models used in research in hypersensitivity reactions in the respiratory tract.