Microbiology AN INTRODUCTION EIGHTH EDITION

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1 TORTORA FUNKE CASE Microbiology AN INTRODUCTION EIGHTH EDITION Differentiate between innate and acquired immunity. Chapter 17 Specific Defenses of the Host: The Immune Response B.E Pruitt & Jane J. Stein PowerPoint Lecture Slide Presentation prepared by Christine L. Case Specific Defenses of the Host: The Immune Response Innate (nonspecific Immunity Differentiate between immunity and nonspecific resistance. Antigen (Ag Antibody (Ab Defenses against any pathogen, genetically predetermined resistance (gender, age, nutrition Specific antibody and lymphocyte response to an antigen (counteract infection A substances that causes the body to produce specific or sensitized T cells Proteins made in response to an antigen Acquired immunity Naturally acquired active immunity Serology Antiserum Globulins Gamma (γ globulin Terminology Resistance to infection during life of host Resulting from infection, may be long-lasting Study of reactions between and antigens Generic term for serum because it contains Ab Serum proteins Serum fraction containing Ab Serum Proteins separation by gel electrophoresis The Immune Response Immune serum globulin or gamma globulin Figure 17.2 Differentiate between humoral (antibody-mediated and cell-mediated immunity. Acquired immunity Developed during an (vaccination individual's lifetime Humoral immunity Involves Ab ( (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

2 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 Antigenic Determinants (epitopes Antibodies recognize and react with antigenic determinants or epitopes (specific regions on surface of antigen. Antigens cause body to produce specific. Are components of invading microbes generally. Define antigen and hapten. Figure 17.3 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. Antibody Structure (Immunoglobulin protein produced by B cells in response to antigen Explain the function of and describe their structural and chemical characteristics. Figure 17.4 Figure 17.5a-c IgG IgM Name one function for each of the five classes of. Monomer (single bivalent antibody unit 80% of serum Fix complement In blood, lymph, intestine Cross placenta Enhance phagocytosis; neutralize toxins & viruses; protects fetus & newborn Half-life = 23 days Pentamer (5 monomers 5-10% of serum Fix complement In blood, lymph, on B cells Agglutinates microbes; first Ab produced in response to infection Half-life = 5 days

3 IgA IgD Dimer 10-15% of serum In secretions Mucosal protection Half-life = 6 days Monomer 0.2% of serum In blood, lymph, on B cells On B cells, initiate immune response Half-life = 3 days IgE Monomer 0.002% of serum On mast cells and basophils, in blood Allergic reactions; lysis of parasitic worms Half-life = 2 days Involved in allergic reactions Clonal Selection Name the function of B cells. Humoral (fluid immunity involves 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. Differentiation of T cells and B cells, both from stem cells in adult red bone marrow or fetal liver

4 Define apoptosis, and give a potential medical application. Apoptosis normal B cell below, B cell above undergoing apoptosis (bubblelike blebs Programmed cell death to prevent overpopulation of B cells 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 ( and memory cells Describe the clonal selection theory. Figure 17.8 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 Protective Mechanism of Ag-Ab Binding Result of antigenantibody binding Tags foreign cells and molecules for destruction by phagocytes and complement (serum proteins for phagocytosis and lysis of cells Figure 17.9 Primary and secondary immune response to antigen Monoclonal Antibodies IgM appears first (primary response IgG follows and provides longer-term immunity (high antibody titer Distinguish a primary from a secondary immune response. Figure Define monoclonal 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

5 Monoclonal Antibodies Immune system cells communicate via cytokines Identify at least one function of each of the following in cellmediated immunity: cytokines, interleukins, interferons. Interleukin-1 Interleukin-2 Interleukin-12 γ-interferon Chemokines Stimulates T H cells Activates T H, B, T C, and NK cells Differentiation of CD4 cells Increase activity of macrophages Cause leukocytes to move to an infection Chemical messengers: Cytokines Cell-Mediated Immunity 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 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 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

6 Dendritic cells present antigens T Cells Describe at least one function for each of the following: T H 1 cell, T H 2 cell, T C cell, T D cell, T S cell, APC, MHC,activated macrophage, NK cell. Helper T Cells (CD4, T H T H 1 Activate cells related to cell-mediated immunity T H 2 Activate B cells to produce eosinophils, IgM, and IgE Cytotoxic T Cells (CD8, T C Destroy target cells with perforin Figure T Cells Helper T Cells Delayed Hypersensitivity T Cells (T D Associated with allergic reaction, transplant rejection, and tuberculin skin test Suppressor T cells (T S Turn off immune response when Ag no longer present Figure Cell-mediated Cytotoxicity Nonspecific Cells Activated Macrophages Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines Natural killer cells: Lymphocytes that destroy virusinfected cells, tumor Figure Figure 17.15

7 T-independent Antigens T-indep. antigen has repeating units that cross-link several antigen receptors on same B cell B cell Describe the role of and NK cells in antibody-dependent cellmediated cytotoxicity. Compare and contrast T-dependent antigens and T-independent antigens. T-independent Antigens Antibody-Dependent Cell-Mediated Cytotoxicity Compare and contrast cell-mediated and humoral immunity. How helper T cells may activate B cells to make against T- dependent antigens Eosinophils adhering to larval stage of parasitic fluke Figure Figure Duality of immune system