18- adaptive immune - 1 Lecture Notes: Immune System (Part...

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1 Lecture Notes: Immune System (Part II: Adaptive Immune System) THIS IS THE FIRST PART OF A LECTURE ON THE ADAPTIVE IMMUNE SYSTEM ANOTHER PART OF TO THIS LECTURE WILL FOLLOW! I. Adaptive or Specific Immune System A. General Characteristics 1. Specific so that it can eliminate with equal precision almost any type of pathogen 2. Functional System a. can eliminate specific foreign substances as well as abnormal body cells b. can magnify the inflammatory response i. responsible for most complement activation 3. Must be primed by an initial exposure to a specific foreign substance called an antigen a. takes time B. History 1. experiments in the late 1800s found that there were protective factors in the blood that defended against future infection by the same pathogen a. protective factors are proteins called antibodies b. these factors could be transferred to other organisms that were not exposed to the antigen 2. important findings about the adaptive immune response a. antigen-specific b. systemic c. has “memory” C. Two branches of adaptive immunity 1. Humoral immunity or antibody-mediated immunity consists of antibodies circulating in the fluids of the body a. produced by lymphocytes or their offspring 2. Cellular or cell-mediated immunity – lymphocytes themselves a. Targets – virus or parasite-infected tissue cells, cancer cells, foreign graft cells b. can act directly by lysing foreign cells or indirectly by releasing chemicals that enhance the inflammatory response or activate other lymphocytes or macrophages. II. Antigens A. Antigens vs. Haptens 1. Antigens – substances that can mobilize the immune system and provoke an immune response a. most large, complex molecules that are NOT normally present in the body b. help distinguish “self” from “nonself” 2. Complete antigens a. have immunogenicity – the ability to stimulate formation of specific lymphocytes and antibody production b. have reactivity – the ability to react with the lymphocytes and antibodies c. antigens include nearly all foreign proteins, nucleic acids, lipids, and many large polysaccharides. i. proteins are the strongest antigens d. other antigens can be pollen grains or microorganisms e. generally small molecules like peptides, nucleotides, and many hormones are NOT immunogenic
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2 f. these small particles can link with other substances though and become immunogenic i. allergies 3. Haptens – small molecules that are reactive but not immunogenic unless attached to a protein carrier B. Antigenic Determinants 1. only certain parts of an antigen is immunogenic. This part is known as the antigenic determinant 2. free antibodies or activated lymphocytes bind to these antigenic determinants 3. a single antigen can have a variety of antigenic determinants and stimulate many different kinds of antibodies 4. large simple molecules that have many regularly repeating units (not chemically complex) are not very immunogenic. C.
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This note was uploaded on 10/19/2011 for the course PCB 3703C taught by Professor Asd during the Spring '09 term at University of Central Florida.

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18- adaptive immune - 1 Lecture Notes: Immune System (Part...

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