1 / 41

Chapter 17

Chapter 17. Specific Defenses of the Host: The Immune Response. Differentiate between innate and acquired immunity. Specific Defenses of the Host: The Immune Response. Differentiate between immunity and nonspecific resistance.

xanthe
Download Presentation

Chapter 17

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


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

  2. Differentiate between innate and acquired immunity.

  3. Specific Defenses of the Host:The Immune Response Differentiate between immunity and nonspecific resistance. • Innate (nonspecific) Defenses against any pathogen, genetically predetermined resistance (gender, age, nutrition) • Immunity Specific antibody and lymphocyte response to an antigen (counteract infection) • 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

  4. Terminology • Acquired immunity Resistance to infection during life of host • Naturally acquired Resulting from infection, may be active immunity long-lasting • 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

  5. Serum Proteins – separation by gel electrophoresis • Immune serum globulin or gamma globulin Figure 17.2

  6. The Immune Response Differentiate between humoral (antibody-mediated) and cell-mediated immunity. • Acquired immunity Developed during an (vaccination) individual's lifetime • Humoral immunity Involves Ab (antibodies) (in body fluids) produced by B cells • Defend against bacteria, viruses, toxins in blood plasma and lymph • Cell-mediated immunity Involves T cells (certain lymphocytes) • Response to intracellular bacteria, viruses, parasites, transplanted tissue, cancer cells

  7. Acquired Immunity Contrast the four types of acquired immunity. • Naturally acquired active immunity • Resulting from infection • Naturally acquired passive immunity • Transplacental or via colostrum • Artificially acquired active immunity • Injection of Ag (antigen - vaccination) • Artificially acquired passive immunity • Injection of Ab (antibody) or antiserum

  8. Antigenic Determinants (epitopes) Define antigen and hapten. • Antibodies recognize and react with antigenic determinants or epitopes (specific regions on surface of antigen). • Antigens cause body to produce specific antibodies. Are components of invading microbes generally. Figure 17.3

  9. Haptens • Hapten is a molecule too small to stimulate antibody formation by itself, until combined with larger carrier molecule like a serum protein, becoming an antigen. Figure 17.4

  10. Antibody Structure (Immunoglobulin) – protein produced by B cells in response to antigen • Explain the function of antibodies and describe their structural and chemical characteristics. Figure 17.5a-c

  11. IgG antibodies Name one function for each of the five classes of antibodies. • Monomer (single bivalent antibody unit) • 80% of serum antibodies • Fix complement • In blood, lymph, intestine • Cross placenta • Enhance phagocytosis; neutralize toxins & viruses; protects fetus & newborn • Half-life = 23 days

  12. IgM antibodies • Pentamer (5 monomers) • 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. 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 • Involved in allergic reactions

  16. Clonal Selection Name the function of B cells. • Humoral (fluid) immunity involves antibodies produced by B cells • Bone marrow gives rise to B cells. • Mature B cells migrate to lymphoid organs. • A mature B cells recognizes epitopes (antigen receptor).

  17. Differentiation of T cells and B cells, both from stem cells in adult red bone marrow or fetal liver

  18. Define apoptosis, and give a potential medical application. • Apoptosis – normal B cell below, B cell above undergoing apoptosis (bubble-like blebs) • Programmed cell death to prevent overpopulation of B cells

  19. Clonal Selection & Differentiation of B cells • Each particular B cell recognizes only one type of antigen, activating the B cell • Produces clone of plasma cells (antibodies) and memory cells Describe the clonal selection theory. Figure 17.8

  20. Self-tolerance Explain how an antibody reacts with an antigen; identify the consequences of the reaction. • Antigen-antibody complex can result in agglutination, inflammation, lysis • Body doesn't make Ab against self • Clonal deletion • The process of destroying B and T cells that react to self antigens • Amount of antibody in serum called antibody titer

  21. Protective Mechanism of Ag-Ab Binding • Result of antigen-antibody binding • Tags foreign cells and molecules for destruction by phagocytes and complement (serum proteins for phagocytosis and lysis of cells) Figure 17.9

  22. Primary and secondary immune response to antigen • Distinguish a primary from a secondary immune response. • IgM appears first (primary response) • IgG follows and provides longer-term immunity (high antibody titer) Figure 17.10

  23. Monoclonal Antibodies Define monoclonal antibodies and identify their advantage over conventional antibody production. • Hybridomas are produced by fusing a cancer cell with an Ab-secreting plasma cells • The hybridoma cell culture is immortal and produces monoclonal Abs (Mabs) – serologic identification tests, prevent tissue rejections • Immunotoxins: Mabs conjugated with a toxin to target cancer cells • Chimeric Mabs: Genetically modified mice that produce Ab with a human constant region • Humanized Mabs: Mabs that are mostly human, except for mouse antigen-binding

  24. Monoclonal Antibodies

  25. Immune system cells communicate via cytokines • Identify at least one function of each of the following in cell-mediated immunity: cytokines, interleukins, interferons. • Interleukin-1 Stimulates TH cells • Interleukin-2 Activates TH, B, TC, and NK cells • Interleukin-12 Differentiation of CD4 cells • -Interferon Increase activity of macrophages • Chemokines Cause leukocytes to move to an infection

  26. Chemical messengers: Cytokines • Cells of immune system communicate via cytokines • Interleukins (IL) are cytokines between leukocytes • Interferons protect cells against viruses • Chemokines cause leukocytes to move to infection site

  27. Cell-Mediated Immunity • Specialized lymphocytes, mostly T cells, respond to intracellular Ags • After differentiating in the thymus, T cells migrate to lymphoid tissue • T cells differentiate into effector T cells when stimulated by an Ag • Some effector T cells become memory cells

  28. Pathogens entering the gastrointestinal or respiratory tracts pass through: • M (microfold) cells in • Peyer's patches which contains • Dendritic cells which are antigen-presenting cells and • T cells

  29. Dendritic cells present antigens Figure 17.12

  30. T Cells Describe at least one function for each of the following: TH1 cell, TH2 cell, TC cell, TD cell, TS cell, APC, MHC,activated macrophage, NK cell. • Helper T Cells (CD4, TH) • TH1 Activate cells related to cell-mediated immunity • TH2 Activate B cells to produce eosinophils, IgM, and IgE • Cytotoxic T Cells (CD8, TC) • Destroy target cells with perforin

  31. T Cells • Delayed Hypersensitivity T Cells (TD) • Associated with allergic reaction, transplant rejection, and tuberculin skin test • Suppressor T cells (TS) • Turn off immune response when Ag no longer present

  32. Helper T Cells Figure 17.13

  33. Cell-mediated Cytotoxicity Figure 17.14

  34. Nonspecific Cells – Activated Macrophages • Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines • Natural killer cells: Lymphocytes that destroy virus-infected cells, tumor Figure 17.15

  35. T-independent Antigens • T-indep. antigen has repeating units that cross-link several antigen receptors on same B cell B cell Compare and contrast T-dependent antigens and T-independent antigens.

  36. Describe the role of antibodies and NK cells in antibody-dependent cell-mediated cytotoxicity.

  37. T-independent Antigens • How helper T cells may activate B cells to make antibodies against T-dependent antigens Figure 17.16

  38. Antibody-Dependent Cell-Mediated Cytotoxicity Compare and contrast cell-mediated and humoral immunity. • Eosinophils adhering to larval stage of parasitic fluke Figure 17.18

  39. Duality of immune system

More Related