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Unformatted text preview: Chapter 62 INTRODUCTION TO IMMUNOLOG Y In the introductory material in Chapter 60, it was noted that the primary barriers between the animal and the environment, the various epithelial surfaces, are less than perfect in protecting the internal environment of the animal. Animals have a highly specialized line of defense that has unique properties and incredible power to protect the integrity of the internal environment. Study of the immune system, or immunology , has progressed rapidly to the extent that it has budded off as a distinct discipline area. It is of great importance in animal health, and knowledgeable use of immune biology certainly has a major place in modem animal health and management. The description of immunity provided here is of an introductory nature and is quite superficial. Excellent, comprehensive, texts of immunology are available to readers seeking more detail and more authoritative treatment of the topic. The remainder of this chapter is focused on the immune system and aspects of its operation. Chapter 63 will describe, in a more integrated context, how the immune system and related mechanisms enable animals to respond to cutaneous injuries. A. Introductory description Substances that are foreign to an animal are often capable of initiating an immune response when they are introduced to that animal. The substance is first recognized as being foreign, or non-self, by cells of the lymphoid system, and a complex series of reactions is set in motion. For convenience, these are separated into two categories of immune responses - innate and acquired. Innate immunity describes mechanisms, mainly cellular in nature, that pre-exist in an individual and can spring into action immediately to deal with a foreign threat. Acquired immunity , involving both cell- mediated and antibody-mediated processes, implies a systematic enhancement of immune defenses against specific threats. In nature, this is provoked whenever foreign substances have been detected and is a "follow-up" to operation of the innate immune system. When human intervention is used to immunize an animal by vaccination, acquired immunity is the result, and antibodies are produced in the immunized animal. Substances that are capable of evoking an immune response are called immunogens . These can be isolated molecules, molecular fragments or molecular components of foreign cells (including pathogens), and even of non-cellular infectious agents like viruses. There is a tendency for larger molecules to be more effective immunogens than are smaller molecules. For example, large proteins, especially the glycoproteins, initiate antibody production more readily than do very small peptides. Complex carbohydrates and lipids are also potent immunogens, so it is no surprise that the plasmalemma of foreign cells, or the cell wall substances of microorganisms, may be quite immunogenic....
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This note was uploaded on 03/23/2009 for the course ANSCI 1110 taught by Professor Brucecurrie during the Fall '08 term at Cornell University (Engineering School).
- Fall '08