Page 47 - Veterinary Immunology, 10th Edition

VetBooks.ir LEARNING OBJECTIVES

After reading this chapter, you should be able to:

• Understand how the body detects both invading microbes and tissue damage by
using specific receptors that bind conserved microbial molecules (PAMPs) as
well as molecules released by broken cells (DAMPs).

• Understand how PAMPs and DAMPs bind to pattern-recognition receptors
(PRRs) found on cell surfaces or inside cells.
• Understand how microbial nucleic acids can be detected by innate receptors.

• Describe how other triggering signals come from damaged tissues or broken
cells.
• Understand that the most important family of PRRs consists of the toll-like

receptors (TLRs).
• Recognize the significance of lipopolysaccharides and other conserved microbial
molecules in triggering innate immune responses.

• List four major populations of sentinel cells.
• List some microbial molecules that trigger responses by toll-like receptors.

• Define pattern recognition receptors; damage-associated molecular patterns;
pathogen-associated molecular patterns; caspases; lectins; selectins.

Bacteria and viruses multiply very rapidly. A single bacterium with
a doubling time of 50 minutes can produce about 500 million
offspring within 24 hours. When these microbes invade the body

they must be destroyed before they can overwhelm its defenses.
Time is of the essence, and delay can be fatal. The body must
therefore employ fast-acting response mechanisms as its first line of

defense against invaders. These mechanisms need to be on constant
standby and respond to the first signs of microbial invasion. They
constitute the innate immune system.
Because all multicellular organisms are subject to microbial
attack, innate immunity has evolved in animals and plants, in

vertebrates, and in invertebrates. Innate immune mechanisms have
evolved in different ways and at different times in response to
different threats. As a result, the innate immune system consists of

many diverse subsystems or modules. The most important of these

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