Page 1083 - Veterinary Immunology, 10th Edition

VetBooks.ir LEARNING OBJECTIVES

After reading this chapter, you should be able to:

• Explain how some antigens, when injected into the skin, induce a slowly
developing inflammatory response called delayed, or type IV, hypersensitivity.
• Understand how delayed hypersensitivity reactions are mediated by T cells and

natural killer (NK) cells.
• Describe the tuberculin response and its importance in detecting tuberculosis.
• Describe the process of tubercle formation.

• Explain the pathogenesis of allergic contact dermatitis.
• Describe the major skin-loss disorders seen in animals.
• Describe why in vitro assays for cell-mediated immunity must focus on detecting

secreted cytokines or measuring cell division.
• Explain how in vivo assays for cell-mediated responses generate a biological
response such as the development of a delayed hypersensitivity skin reaction or

the rejection of an allograft.
• Describe the basic principles of the IFN release assay, the lymphocyte

stimulation assay, the chromium release assay, intradermal mitogen testing,
and the ELISpot assay
• Describe how T cell or NK cell cytotoxicity can be measured.

Certain antigens, when injected into the skin of sensitized animals,

provoke inflammation at the injection site after a delay of 12 to 24
hours. These delayed hypersensitivity reactions are classified as
type IV hypersensitivities and result from interactions between the
injected antigen and T cells. An important example of a delayed

hypersensitivity reaction is the tuberculin response. This is an
inflammatory response that develops in the skin of an animal
infected with tuberculosis following intradermal injection of
tuberculin. Delayed hypersensitivity reactions can be considered T
cell–mediated inflammatory responses directed against organisms

that are resistant to elimination by conventional responses.

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