The Adaptive Immune Response on line.ppt

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  • 1. The Adaptive Immune Response “Match me perfectly and I’m neutralized” Kathy Huschle Northland Community and Technical College
  • 2. Adaptive Immune Response
    • in contrast to the innate immune response which we are basically born with, the adaptive immune response is an ever developing system
      • it continues to mature throughout our life
  • 3. Adaptive Immune Response
      • in most cases as each new microbial invader is encountered, our adaptive immune response initiates a specific attack against the invader
      • generally this invader is remembered and that “memory” is readily available in the case of a second or subsequent attack from the same invader
  • 4. Adaptive Immune Response
    • this system is an extremely complex system to which we will attempt to gain a basic understand
    • immunologists are continually discovering many facts about the adaptive immune response
  • 5. Adaptive Immune Response
    • the adaptive immune response
      • is learned or acquired
      • recognizes specific substances foreign to the body
      • is essential for life
  • 6. Adaptive Immune Response
    • other terms used for the adaptive immune response include
      • acquired immunity
      • specific immunity
    • though at one time thought to function exclusive of the innate immune system, research is now discovering a correlation between the two systems
    • regardless of a correlation or not, the failure of our immune system results in mortality
  • 7. Adaptive Immune Response
    • adaptive immune response is characterized by
      • specificity
      • memory
      • learned ability to recognize (acquired) pathogens which allows the body to usually only suffer once from that particular pathogen
  • 8. Components of the Adaptive Immune System
    • antigens
    • antibodies
    • lymph system
    • lymphocytes
      • B cells
      • T cells
      • NK cell (Natural Killer)
    Antigen Antibody B cell T cell NK cell
  • 9. Antigens
    • the term antigen derives from the two words anti body gene rator
    • most antigens are proteins or large polysaccharides
  • 10. Antigens
    • often a component of invading microbes, such as the capsule, cell wall, flagella, toxin
      • particular chemical that will activate the adaptive immune response
    Antigens found in autologous tumor
  • 11. Antigens
    • invading microbes can have many antigens on its surface
    pathogen
  • 12. Antigens
    • when and antigen elicits an immune response it is often referred to as a immunogen
    • epitope is the reactive portion of the antigen that reacts chemically with an antibody to form the antigen-antibody complex or immune complex
  • 13. Antigens
    • two essential properties of antigens include
      • immunogenicity
        • the ability to stimulate immune system
    antigen-antibody complex
  • 14. Antigens
      • specific reactivity
        • the ability to react with effector molecules (antibody) to form an antigen-antibody complex
    Antigens in red with green borders
  • 15. Antibodies
    • glycoproteins that are also referred to as immunoglobiulins
    • basic structure is a Y shaped molecule with 2 functional parts
      • Fab region
      • Fc region
    Fab region Fc region
  • 16. Antibodies
    • Fab region
      • this is the part of the antibody that binds to the antigen
    • Fc region
      • the stem of the antibody that functions as a “red flag”
        • notifies the rest of the immune system: “here I am, come and help”
  • 17. Fab regions The Fab portion of IgG binds to epitopes of a capsule. The Fc portion can now attach the capsule to Fc receptors on phagocytes for enhanced attachment. Once attached to the phagocyte by way of IgG, the encapsulated bacterium can be engulfed more efficiently and placed in a phagosome
  • 18. Antibodies
    • protection gained from the formation of antigen-antibody complexes basically comes down to the tagging of foreign cells and molecules for destruction by phagocytes and complement
    Antibodies shown in different stains
  • 19. Antibodies
    • the antibody molecule is not damaging to the antigen
    Melanoma antigens
  • 20. Antibodies
    • foreign organisms and toxins are rendered harmless by
      • neutralization
      • immobilization and prevention of adherence
      • agglutination and precipitation
      • opsonization
      • complement activation
      • antibody-dependent cellular cytosis (ADCC)
    Respiratory syncytial virus antigens
  • 21. Antibodies
    • neutralization
      • blocks the adhesion of bacteria and viruses by bathing the surface of the cell with antibody
    • immobilization and prevention of adherence
      • antibodies binding to structures such as flagella and pili can interfere with mobility and attachment
  • 22. Antibodies
    • agglutination and precipitation
      • enhances phagocytosis by gathering antigens into clumps
    • opsonization
      • coating an antigen with antibody enhances phagocytosis
  • 23. Antibodies
    • complement activation
      • enhances cell destruction by cell lysis
    • antibody-dependent cellular cytotxicity
      • antibodies attach to target cells causing destruction by non-specific immune system cells
  • 24. Antibodies
  • 25. Antibodies
  • 26. Antibodies
    • there are 5 classes of immunoglobulins
      • each class plays a different role in the immune response
        • IgG
        • IgM
        • IgA
        • IgD
        • IgE
  • 27. Antibodies
    • IgG
      • enhances phagocytosis
      • neutralizes toxins and viruses
      • protects the fetus and newborn
        • only immunoglobulin that is transferred across the placenta
  • 28. Antibodies
    • IgG
      • circulates in the blood, but can easily exit to the tissues
      • most abundant circulating antibody
    IgG circulating in tissue
  • 29. IgG IgG reacts with epitopes on the host cell membrane. Phagocytes then bind to the Fc portion of the IgG and discharge their lysosomes.
  • 30. Antibodies
    • IgA
      • provides localized protection on mucosal surfaces
      • found in mucus, tears, saliva, sweat, blood, human milk
      • protects surface tissues and prevents adherence of microorganisms
        • this is important in respiratory, gastrointestinal and genitourinary tract infections
  • 31. Antibodies
    • IgM
      • especially effective against microorganisms and clumping antigens
      • these are the first antibodies produced in response to a mild infection
      • are circulating antibodies found in the circulatory system with IgG
  • 32. IgM IgG or IgM reacts with epitopes on the host cell membrane and activates the classical complement pathway. Membrane attack complex (MAC) then causes lysis of the cell.
  • 33. Antibodies
    • IgD
      • function of these antibodies is not yet fully defined
      • it’s presence on B cells functions in the initiation of an immune response
  • 34. Antibodies
    • IgE
      • antibodies responsible for allergic reaction
      • possibly involved in the lysis of parasitic worms
      • found in the blood serum
      • plays a role in the initiation of the inflammatory response
  • 35. Lymphoid System
    • in regards to the immune system the lymphatic system consists of tissues and organs that are designed and located to convey the B and T cells into contact with all antigens that enter the body
  • 36. Lymphoid System
    • this process is accomplished with the
      • lymphatic vessels
      • fluid of the lymphoid system called lymph
      • secondary lymph organs such as tonsils, spleen, lymph nodes
  • 37. Lymphoid System
      • primary lymph organs
        • bone marrow: the location of stem cells that will eventually become B and T cells, B cells mature in the bone marrow
        • thymus: maturation of the T cells
    Healthy bone marrow Bone marrow with leukemia Lymph node
  • 38. Lymphoid System
    • notice how completely our body is covered by the lymphoid system
  • 39. Lymphocytes
    • critical part of immune system responsible for
      • detection of foreign antigens
      • activate immune system
    • B lymphocytes
    • T lymphocytes
    • natural killer cells (NK cells)
  • 40. B lymphocytes: B cells
    • antibody producing cells that respond to an antigen stimulation
    • develop from stem cells located in the red bone marrow of adults and the liver of a fetus
    B Cells dividing
  • 41. B lymphocytes: B cells
    • following maturation, they migrate to the lymphatic tissue
    B cell in lymph node
  • 42. B lymphocytes: B cells
    • once in place in the lymphoid organs, the B cells recognize antigens by means of the antigen receptors found on their cell surfaces
    • basis for antibody-mediated immunity
    B indicates a B cell HIV antigens in yellow B cells in red
  • 43. B cells
  • 44. T lymphocytes: T cells
    • key cellular component of immunity
    • develop from stem cells found in the bone marrow
    • precursors to T cells migrate to the thymus, where they reach maturity
    human T cells
  • 45. T lymphocytes: T cells
    • following maturity, T cells migrate to various lymph organs where they await contact with antigens
    • basis for cell-mediated immunity
    T cells (on left – orange, on right – gray) killing cancer cells (on left- mauve. on right – red)
  • 46. T cells
  • 47. Natural Killer Cells
    • these cells are not immunologically specific
      • they do not need to be stimulated by an antigen
  • 48. Natural Killer Cells
    • capable of destroying other cells, particularly viruses-infected cells and tumor cells
    • also can attack large parasites
  • 49. Clonal Selection of Lymphocytes
    • speaks to the ability of B cells and T cells to differentiate to a population of cells capable of recognizing an infinite number of antigens
      • it is estimated that the human body has approximately 1 billion B cells, yet each individual cell is only capable of recognizing and responding to one antigen
    B cell differentiation
  • 50. Clonal Selection of Lymphocytes
    • terms used to define various stages of clonal selection include
      • immature
      • naïve
      • activated
      • effector
      • memory
  • 51. Clonal Selection of Lymphocytes
    • immature lymphocytes
      • have not fully developed their antigen-specific receptor
    • naïve lymphocytes
      • have an antigen receptor, but have not encountered the antigen
    immature lymphocyte
  • 52. Clonal Selection of Lymphocytes
    • activated lymphocytes
      • have received confirmation of the danger of the antigen and are able to proliferate more lymphocytes specific for that antigen
    • effector lymphocytes
      • descendents of activated lymphocytes
    Activated lymphocyte
  • 53. Clonal Selection of Lymphocytes
    • memory lymphocytes
      • long-lived descendents of activated lymphocytes
      • can revert back to activated lymphocytes with stimulation from the same antigen
  • 54. Antibody-Mediated Immunity
    • humoral or antibody-mediated immunity involves antibodies that are produced by B cells
      • the term humoral is derived from the word “humors”, which is Latin for fluid
    • in response to foreign antigens, the B cell is activated to produce a clone of plasma cells and memory cells
      • plasma cells secrete antibodies
      • memory cells recognize pathogens from previous encounters
        • B memory cells are long lived and are ready to mount an attack the next time that specific antigen presents itself
  • 55. Primary & Secondary Response The body can make low levels of soluble antibody about one week after exposure to antigen. However, a second exposure to antigen produces a much faster response, and several orders of magnitude higher levels of antibody. The ability of antibody to bind antigen also increases in the secondary response. The memory of antigen and stimulated response is the basis for vaccination
  • 56. Antibody-Mediated Immunity
    • the antigen-antibody complexes that are formed as a result of antibodies produce by B plasma cells attract phagocytes
    Bacteria in green
  • 57. Antibody-Mediated Immunity
    • phagocytosis destroys the pathogen and control of the disease is accomplished
    Bacteria
  • 58. Cell-Mediated Immunity
    • cell-mediated immunity involves specialized lymphocytes that respond to intracellular antigens
    • T cells are responsible for managing cell-mediated immunity
      • after maturation in the thymus, T cells differentiate into 2 groups
        • T-cytotoxic cells and T helper cells
    Cytotoxic T cells Helper T cell
  • 59. Cell-Mediated Immunity
    • recognizes modified host cells (abnormal cells)
      • cell-mediated immunity is critical to controlling infections where pathogens reproduce in human cell
        • viruses, bacteria (rickettes), protozoa
        • important role in recognizing and destroying abnormal cells, such as tumor cells
    T cells attacking cancer
  • 60. Cell-Mediated Immunity
      • T cells do not recognize free antigens, the antigen must be presented by a modified host cell
    • augments antibody-mediated immunity
      • eliminates cells infected with viruses
      • antibodies can’t penetrate a virus within a host cell
    T cells
  • 61. Cell-Mediated Immunity
    • response to intracellular agents includes
      • antigen presentation
        • the antigen must be processed (degraded) and then individual peptides are displayed on the surface of a glycoprotein called a major histocompatibility complex (MHC) molecule
        • this antigen processing is done by antigen presenting cell (APC)
  • 62. Cell-Mediated Immunity
    • cytotoxic T cells recognize the non-self cell and induce apoptosis (cell self death) in the viral infected or other microbial infected cell
      • this process also recognizes cancer cells and destroys them
      • unfortunately this process also recognizes and destroys non-self tissue or organ transplants
  • 63. Cell-Mediated Immunity
    • T-helper cells, often referred to as CD4 cells, are responsible for the “second opinion” in immunity
      • T-helper cells judge the significance of the antigen presented by the antigen-presenting cells (APC)
  • 64. Cell-Mediated Immunity
      • after binding to an APC, T- helper cells secrete cytokines that activate other T cells and B cells
        • interleukin-2
        • macrophage chemotactic factor
        • migration inhibition factor
        • macrophage activating factor
        • macrophage colony stimulating factor
  • 65. Cell-Mediated Immunity
    • interleukin-2
      • stimulates the production of more T cells
    • macrophage chemotactic factor (MCF)
      • attracts macrophages (phagocytes) to the site of infection or abnormality
    • migration inhibition factor (MIF)
      • once at the infection site, MIF inhibits the macrophages from migrating elsewhere in the body
    T cell (yellow) attracting Macrophage (blue)
  • 66. Cell-Mediated Immunity
    • macrophage activating factor (MAF)
      • once at the infection site, MAF alters the function of the macrophages
      • increases their lysosomal activities
        • increases their ability to kill
    Macrophage using pseudopodia to grab pathogen Macrophage ingesting bacteria
  • 67. Cell-Mediated Immunity
    • macrophage colony stimulating factor (CSF)
      • regulates the production of macrophages at the site
    Macrophage and T cell Macrophage & E.coli
  • 68. T-Helper Cells T helper cells also play a role in activating B cells in antibody-mediated immunity
  • 69. Helper T cells Click icon to learn more about T-cell dependent antigens
  • 70. Overview of Antibody-Mediated Immunity
    • initial response (bacteria with antigens enters the body)
    • B cells recognize
    • differentiate into plasma and memory cells
    • memory: recurring exposures
    • plasma produce antibodies
    • antigen/antibody complex forms
    • phagocytosis
    • control of disease
  • 71. Overview of Cell-Mediated
    • modified host cell arrives
    • T cells activated
    • secrete cytokines
    • increase of T cell reproduction
    • attraction of macrophages (MCF)
    • inhibit migration (MIF)
    • activate phagocytosis (MAF)
    • control of disease
  • 72. Overview of Immunity
  • 73. Summary