ABSTRACT
This chapter explores how the components of the adaptive immune system described previously can interact to produce a series of distinct and standard immune responses. These standard immune responses are generally termed ‘hypersensitivity mechanisms’. A hypersensitivity response involves sensitization to an antigen by prior exposure (often repeated and over time). Once an individual is sensitized, subsequent re-exposure to that antigen may lead to an inappropriately excessive immune response termed a hypersensitivity reaction. Hypersensitivity is often equated to allergy, where repeated exposure to antigen (termed ‘allergen’) leads to immunological sensitization and an inappropriate allergic response on re-exposure. In this context, the hypersensitivity or allergic response has led to unwanted tissue pathology
At the end of this chapter you should be able to: • Define hypersensitivity. • Discuss the Gell and Coombs classification
of hypersensitivity and the mechanisms underlying types I-IV hypersensitivity.
