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Chapter 17, part A

Chapter 17, part A. Specific Defenses of the Host: The Immune Response. Specific Defenses of the Host: The Immune Response. Innate (nonspecific) Defenses against any pathogen Immunity Specific antibody and lymphocyte response to an antigen

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Chapter 17, part A

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  1. Chapter 17, part A Specific Defenses of the Host: The Immune Response

  2. Specific Defenses of the Host:The Immune Response • Innate (nonspecific) Defenses against any pathogen • Immunity Specific antibody and lymphocyte response to an antigen • Antigen (Ag) A substances that causes the body to produce specific antibodies or sensitized T cells • Antibody (Ab) Proteins made in response to an antigen

  3. Terminology • Serology Study of reactions between antibodies and antigens • Antiserum Generic term for serum because it contains Ab • Globulins Serum proteins • Gamma () globulin Serum fraction containing Ab

  4. Serum Proteins Figure 17.2

  5. The Immune Response - Two arms • Acquired immunity Developed during an individual's lifetime • Humoral immunity Involves Ab produced by B cells • Cell-mediated immunity Involves T cells

  6. Acquired Immunity • Natural Acquired • Artificially Acquired • Active • Passive • Naturally acquired active immunity • Resulting from infection • Naturally acquired passive immunity • Transplacental or via colostrum • Artificially acquired active immunity • Injection of Ag (vaccination) • Artificially acquired passive immunity • Injection of Ab

  7. Antigenic Determinants • Antibodies recognize and react with antigenic determinants or epitopes. Figure 17.3

  8. Haptens Figure 17.4

  9. Antibody Structure Figure 17.5a-c

  10. IgG antibodies • Monomer • 80% of serum antibodies • Fix complement • In blood, lymph, intestine • Cross placenta • Enhance phagocytosis; neutralize toxins & viruses; protects fetus & newborn • Half-life = 23 days

  11. Compare Ig classes • Be able to compare classes • See table in text

  12. J Chain C4 IgM antibodies • Pentamer • 5-10% of serum antibodies • Fix complement • In blood, lymph, on B cells • Agglutinates microbes; first Ab produced in response to infection • Half-life = 5 days

  13. Secretory Piece J Chain IgA antibodies • Dimer • 10-15% of serum antibodies • In secretions • Mucosal protection • Half-life = 6 days

  14. IgD antibodies • Monomer • 0.2% of serum antibodies • In blood, lymph, on B cells • On B cells, initiate immune response • Half-life = 3 days

  15. IgE antibodies • Monomer • 0.002% of serum antibodies • On mast cells and basophils, in blood • Allergic reactions; lysis of parasitic worms • Half-life = 2 days

  16. Clonal Selection • Bone marrow gives rise to B cells. • Mature B cells migrate to lymphoid organs. • A mature B cells recognizes epitopes.

  17. Clonal Selection Figure 17.8

  18. Self-tolerance • Body doesn't make Ab against self • Clonal deletion • The process of destroying B and T cells that react to self antigens

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