immunity n.
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  1. Immunity Chapter 10

  2. Early Advances • Edward Jenner developed vaccine against smallpox • Pasteur demonstrated that heating could kill microorganisms in food and beverages • Koch linked a microorganism with a specific disease (anthrax)

  3. Three Lines of Defense • Barriers at body surfaces • Nonspecific responses • Immune responses

  4. Barriers at Body Surface • Intact skin and mucous membranes • Lysozyme • Normal bacterial flora • Flushing effect and low pH of urine

  5. Nonspecific Responses • Lymph nodes trap and kill pathogens • Natural killer cells attack a range of targets • Inflammation

  6. Complement System • Plasma proteins that take part in both specific and nonspecific response • Activation of one triggers cascade of reactions that activate others LYSIS OF TARGET CASCADE REACTION FORMATION OF ATTACK COMPLEXES

  7. Acute Inflammation • Nonspecific response to foreign invasion, tissue damage, or both • Destroys invaders, removes debris, and prepares area for healing • Characterized by redness, swelling, warmth, and pain

  8. Inflammation • Mast cells release histamine • Capillaries dilate and leak • Complement proteins attack bacteria • White cells attack invaders and clean up

  9. Features of Immune Responses • Self/nonself recognition • Specificity • Diversity • Memory

  10. Antigens • “Nonself” markers on foreign agents and altered body cells such as tumors • Trigger division of B and T cells

  11. Memory and Effector Cells • When a B or T cell is stimulated to divide, it produces more than one cell type • Memory cells are set aside for future use; they are the basis for immune memory • Effector cells engage and destroy the current threat

  12. Steps in Immune Response • Recognition of an antigen • Rounds of cell division that form huge populations of lymphocytes • Specialization of lymphocytes into effector and memory cells that have receptors for one kind of antigen

  13. Key Components of Immune Response • MHC markers • Antigen-presenting cells • T cells • B cells • Natural killer cells

  14. Overview of Interactions Antibody-mediated response Cell-mediated response Antigen-presenting cell Naive helper T cell Naive B cell Naive cytotoxic T cell Effector B cell Activated helper T cell Effector cytotoxic T cell

  15. B and T Cell Specificity • All the antigen receptors of a given B or T cell are identical • B cells acquire unique antigen-binding receptors in marrow • T cells acquire unique antigen-binding receptors in thymus

  16. antigen Clonal Selection • Only the B cell with antigen-receptor that matches antigen is stimulated to divide • Mitosis yields many cells with that receptor

  17. Immunological Memory • Memory cells specific for an antigen are quickly activated to divide upon subsequent exposure to that antigen Primary Immune Response: naïve T or B cell effector cells memory cells Secondary Immune Response: effector cells memory cells

  18. Lymphocyte Battlegrounds • Lymph nodes filter antigens from body fluids • Macrophages, dendritic cells, B and T cells in nodes and spleen mount a defense

  19. Antibody-Mediated Response • Carried out by B cells • Targets are intracellular pathogens and toxins • Antibodies bind to target and mark it for destruction by phagocytes and complement

  20. Antibody Structure • Antibody consists of four polypeptide chains • Certain parts of each chain are variable; impart antigen specificity

  21. Antibody- Mediated Response • Virgin B cell becomes antigen-presenting B cell • Helper T cell binds to antigen-MHC complex on the B cell • Interleukins stimulate B cell division and differentiation • Effector cells secrete antibodies Naive B cell Antigen-presenting B cell Helper T cell Interleukins Effector B cell secretes antibodies Memory B cell

  22. 5 Classes of Immunoglobulins IgG, IgD, and IgE IgA IgM

  23. Another macrophage Cell-Mediated Response One macrophage • Carried out by T cells • Stimulated by antigen-presenting macrophages • Main target is antigen-presenting body cells (cells with intracellular pathogens) or tumor cells interleukins Cytotoxic T cell Helper T cell interleukins Infected body cell

  24. Organ Rejection • Cytotoxic T cells can contribute to rejection of transplanted tissue • They recognize a portion of the donor cell’s MHC complex as self, view a portion as foreign • Treat the combination as an antigen-MHC complex and attack donor cells

  25. Monoclonal Antibodies • Manufacture antibodies against tumor-specific antigens • First created by fusing antigen-producing B cells from mice with cells from B cell tumors • Now made in genetically engineered cells

  26. Lymphokine-Activated Killers • Lymphocytes are extracted from tumors • Extracted cells are exposed to a lymphokine, an interleukin • Large population of tumor-infiltrating, activated lymphocytes is then reinjected into patient

  27. Immunization • Process that promotes immunity • Active immunization - • Antigen-containing material is injected • Confers long-lasting immunity • Passive - • Purified antibody is injected • Protection is short lived

  28. Allergies • Immune reaction to a harmless substance • Genetic predisposition • IgE responds to antigen by binding to mast cells and basophils • These cells secrete the substances that cause symptoms

  29. Anaphylactic Shock • A life-threatening allergic reaction • Caused by the release of histamine by many mast cells and basophils • Airways constrict and blood pressure drops as capillary permeability soars

  30. Autoimmune Disorders • Immune system makes antibodies against self antigens • Grave’s disease • Myasthenia gravis • Rheumatoid arthritis

  31. SCIDs • Severe combined immunodeficiency • Body’s ability to make lymphocytes is impaired or nonexistent • High vulnerability to infection • ADA deficiency is a heritable SCID • Has been successfully treated using gene therapy