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Chapter 16

Chapter 16. Adaptive Immunity. Overview of Adaptive Immunity. Adaptive immunity is the body’s ability to recognize and defend itself against distinct invaders and their products Five attributes of adaptive immunity Specificity Inducibility Clonality Unresponsiveness to self Memory.

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Chapter 16

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  1. Chapter 16 Adaptive Immunity

  2. Overview of Adaptive Immunity • Adaptive immunity is the body’s ability to recognize and defend itself against distinct invaders and their products • Five attributes of adaptive immunity • Specificity • Inducibility • Clonality • Unresponsiveness to self • Memory

  3. Overview of Adaptive Immunity • Involves activity of lymphocytes • Two main types of lymphocytes • B lymphocytes (B cells) • Mature in the bone marrow • T lymphocytes (T cells) • Mature in the thymus • Two types of adaptive immune responses • Humoral immune responses • Cell-mediated immune responses

  4. Overview of Adaptive Immunity [INSERT FIGURE 16.1]

  5. Overview of Adaptive Immunity Animation: Host Defenses: Cell-Medicated Immunity: Overview Animation: Host Defenses: Humoral Immunity: Overview

  6. Elements of Adaptive Immunity • The Tissues and Organs of the Lymphatic System • Screen the tissues of the body for foreign antigens • Composed of lymphatic vessels and lymphatic cells, tissues, and organs

  7. Elements of Adaptive Immunity • The Tissues and Organs of the Lymphatic System • Lymphatic vessels and the flow of lymph • Form a one-way system that conducts lymph from local tissues and returns it to the circulatory system • Lymph is a liquid with similar composition to blood plasma, which arises from fluid leaked from blood vessels into surrounding tissues

  8. Elements of Adaptive Immunity [INSERT FIGURE 16.2]

  9. Elements of Adaptive Immunity • The Tissues and Organs of the Lymphatic System • Lymphoid organs • Primary lymphoid organs • Red bone marrow • Thymus • Secondary lymphoid organs • Lymph nodes • Spleen • Tonsils • Mucosa-associated lymphatic tissue (MALT)

  10. Elements of Adaptive Immunity [INSERT FIGURE 16.3]

  11. Elements of Adaptive Immunity • Antigens • Properties of antigens • Molecules the body recognizes as foreign and worthy of attack • Body recognizes antigens by three-dimensional regions called epitopes • Include components of bacterial cell walls, capsules, pili, and flagella, as well as proteins of viruses, fungi, and protozoa • Food and dust can also contain antigenic particles

  12. Elements of Adaptive Immunity [INSERT FIGURE 16.4a]

  13. Elements of Adaptive Immunity [INSERT FIGURE 16.4b-d]

  14. Elements of Adaptive Immunity • B Lymphocytes (B Cells) and Antibodies • Arise and mature in the red bone marrow • Found primarily in the spleen, lymph nodes, and MALT • Small percentage of B cells circulate in the blood • Major function is the secretion of antibodies

  15. Elements of Adaptive Immunity • B Lymphocytes (B Cells) and Antibodies • Specificity of the B cell receptor (BCR) • Each B lymphocyte has multiple copies of a single type of protein called the B cell receptor • Each B cell generates a single BCR • The two variable regions of the BCR form the antigen-binding sites • Each BCR recognizes only one epitope • The entire repertoire of an individual’s BCRs is capable of recognizing millions of different epitopes

  16. Elements of Adaptive Immunity [INSERT FIGURE 16.5]

  17. Elements of Adaptive Immunity • B Lymphocytes (B Cells) and Antibodies • Specificity and antibody structure • Antibodies are immunoglobulins similar to BCRs • Secreted by activated B cells called plasma cells • Have identical antigen-binding sites and antigen specificity as the BCR of the activated B cell

  18. Elements of Adaptive Immunity [INSERT FIGURE 16.6]

  19. Elements of Adaptive Immunity • B Lymphocytes (B Cells) and Antibodies • Classes of antibodies • Threats confronting the immune system are variable • The class involved in the immune response depends on the type of foreign antigen, the portal of entry, and the antibody function needed • Five different classes of antibodies

  20. Elements of Adaptive Immunity [INSERT TABLE 16.1]

  21. Elements of Adaptive Immunity • B Lymphocytes (B Cells) and Antibodies • Antibody function • Antigen-binding sites are complementary to epitopes • Due to the close match can form strong, noncovalent interactions • Hydrogen bonds and other attractions may also be involved • Antibodies function in several ways • Activation of complement and inflammation • Neutralization • Opsonization • Killing by oxidation • Agglutination • Antibody-dependent cellular cytotoxicity (ADCC)

  22. Elements of Adaptive Immunity [INSERT FIGURE 16.7]

  23. Elements of Adaptive Immunity Animation: Host Defenses: Humoral Immunity: Antibody Function

  24. Elements of Adaptive Immunity • T Lymphocytes (T Cells) • Produced in the red bone marrow and mature under the influence of the thymus • Circulate in the lymph and blood and migrate to the lymph nodes, spleen, and Peyer’s patches • Antigen-binding sites are complementary to epitopes • T cells have T cell receptors (TCRs) on their cytoplasmic membrane

  25. Elements of Adaptive Immunity • T Lymphocytes • Specificity of the T cell receptor (TCR) • TCRs do not recognize epitopes directly • TCRs only bind epitopes associated with a MHC protein • Act primarily against body cells that harbor intracellular pathogens

  26. Elements of Adaptive Immunity [INSERT FIGURE 16.8]

  27. Elements of Adaptive Immunity • T Lymphocytes • Types of T lymphocytes • Based on surface glycoproteins and characteristic functions • Three types • Cytotoxic T lymphocyte – directly kills other cells • Helper T lymphocyte – functions to “help” regulate the activities of B cells and cytotoxic T cells • Regulatory T lymphocyte – represses adaptive immune responses

  28. Elements of Adaptive Immunity Animation: Host Defenses: Cell-Mediated Immunity: Cytotoxic T Cells

  29. Elements of Adaptive Immunity Animation: Host Defenses: Cell-Mediated Immunity: Helper T Cells

  30. Elements of Adaptive Immunity [INSERT TABLE 16.2]

  31. Elements of Adaptive Immunity • Clonal Deletion • Vital that immune responses not be directed against autoantigens • Body eliminates self-reactive lymphocytes via clonal deletion • Lymphocytes that react to autoantigens undergo apoptosis

  32. Elements of Adaptive Immunity [INSERT FIGURE 16.9]

  33. Elements of Adaptive Immunity [INSERT FIGURE 16.10]

  34. Elements of Adaptive Immunity • Immune System Cytokines • Soluble regulatory proteins that act as intercellular signals when released from certain body cells • Immune system cytokines secreted by various leukocytes • The complex web of signals among all the cell types of the immune system is referred to as the cytokine network

  35. Elements of Adaptive Immunity • Immune System Cytokines • Interleukins (ILs) – signal among leukocytes • Interferons (IFNs) – antiviral proteins that may act as cytokines • Growth factors – proteins that stimulate stem cells to divide • Tumor necrosis factor (TNF) – Secreted by macrophages and T cells to kill tumor cells and regulate immune responses and inflammation • Chemokines – chemotactic cytokines that signal leukocytes to move

  36. Preparation for an Adaptive Immune Response • The Roles of the Major Histocompatibility Complex • Group of antigens first identified in graft patients • Important in determining the compatibility of tissues in successful grafting • Major histocompatibility antigens are glycoproteins found in the membranes of most cells of vertebrate animals • Function to hold and position antigenic determinants for presentation to T cells

  37. Preparation for an Adaptive Immune Response • The Roles of the Major Histocompatibility Complex • Antigens bind in the antigen-binding groove of MHC molecules • Two classes of MHC proteins • MHC class I • MHC class II

  38. Preparation for an Adaptive Immune Response [INSERT FIGURE 16.11]

  39. Preparation for an Adaptive Immune Response [INSERT FIGURE 16.12]

  40. Preparation for an Adaptive Immune Response • Antigen Processing • Antigens must be processed for MHC proteins to display epitopes • Antigen processing occurs by different processes for endogenous and exogenous antigens

  41. Preparation for an Adaptive Immune Response Animation: Host Defenses: Antigen Processing and Presentation: Overview

  42. Preparation for an Adaptive Immune Response

  43. Preparation for an Adaptive Immune Response

  44. Preparation for an Adaptive Immune Response Animation: Host Defenses: Antigen Processing and Presentation: Steps

  45. Preparation for an Adaptive Immune Response Animation: Host Defenses: Antigen Processing and Presentation: MHC

  46. Cell-Mediated Immune Responses • Responds to intracellular pathogens and abnormal body cells • The most common intracellular pathogens are viruses but the response is also effective against cancer cells, intracellular protozoa, and intracellular bacteria

  47. Cell-Mediated Immune Responses • Activation of T Cell Clones and Their Functions • Steps involved in activation of cytotoxic T cells • Antigen presentation • Helper T cell differentiation • Clonal expansion • Self-stimulation

  48. Cell-Mediated Immune Responses [INSERT FIGURE 16.14]

  49. Cell-Mediated Immune Responses

  50. Cell-Mediated Immune Responses Animation: Host Defenses: Cell-Mediated Immunity: Cytotoxic T Cells

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