ABSTRACT
In this chapter, the terms antigen and allergen are first defined and differentiated from one another. Sensitization and atopy are also defined within the context of allergy, and the process of allergic inflammation is described. This includes the biochemical mediators of allergic inflammation as well as the clinical outcome of an allergic reaction. The molecular structure of an allergen, its affinity toward an antibody, the route and amount of allergen exposure, and the presence of underlying allergic sensitization are crucial components of an allergic reaction. However, while all proteins may be antigens and stimulate an immune response, not all antigens become allergens. It is likely that a combination of genetics and environmental factors influence the loss of immunologic tolerance and subsequent production of IgE against a particular antigen. Further research is needed to identify these genetic and environmental components.
