Adaptive Immunity:Specific Defenses of the Host(Chapter 17)Lecture MaterialsforAmy Warenda Czura, Ph.D.Suffolk County Community CollegeEastern CampusPrimary Source for figures and content:Tortora, G.J. Microbiology An Introduction 8th, 9th, 10th ed. San Francisco: PearsonBenjamin Cummings, 2004, 2007, 2010.Amy Warenda Czura, Ph.D.1SCCC BIO244 Chapter 17 Lecture SlidesImmunity = resistance: defense against foreign materialInnate immunity = defenses that are alwayspresent to provide instant protection against infectionAdaptive immunity = induced, adapts to a specific foreign substance, acquired memory of the infectionAntigens = substances that provoke an immune response, immunogenic moleculesDual Nature of Adaptive Immune Response:1. Humoral / Antibody-Mediated Immunity-involves antibodies produced by B cells toconfer immunity-best against bacteria, toxins, and virus thatare free in body fluids2. Cell-Mediated Immunity-involves T cells that act against foreignorganisms or tissues-involves cytokines & cytotoxicityAmy Warenda Czura, Ph.D.2SCCC BIO244 Chapter 17 Lecture Slides-works best on bacteria- or virus-infectedcells, fungi, protozoa, tissue grafts andcancerFour Types of Adaptive Immunity:(on handout)Amy Warenda Czura, Ph.D.3SCCC BIO244 Chapter 17 Lecture Slides1. Naturally Acquired Active Immunity-everyday exposure to antigens & disease-development of B and T cell responses &memory, immunity may be life long2. Naturally Acquired Passive Immunity-transfer of antibodies from mother to fetusor infant across placenta or in milk-immunity lasts as long as antibodies, weeksto months3. Artificially Acquired Active Immunity-vaccination / immunization: forced introduction of nonvirulent antigens-development of B and/or T cell responses &memory, immunity may be life long4. Artificially Acquired Passive Immunity-injection of preformed antibodies from people or animals, called antiserum-immunity lasts as long as antibodies, weeksto monthsAmy Warenda Czura, Ph.D.4SCCC BIO244 Chapter 17 Lecture SlidesAntigens:-determine self vs. non-self-non-self provokes immune response-located on the surface of cells: capsules, walls, flagella, fimbriae, pentons,spikes, etc., or toxin molecules-most are proteins or large polysaccharides-the specific antigenic compound recognizedby lymphocytes or antibodies is called theepitope / antigenic determinantAmy Warenda Czura, Ph.D.5SCCC BIO244 Chapter 17 Lecture Slides-lymphocytes have receptors to recognize and specifically bind to the epitope-antibodies have specific antigen-binding sites-a single pathogen or antigen can have hundreds of different epitopes / antigenicdeterminants on its surface, each of whichwould be recognized and bound by a different antibody or lymphocyteAntibodies / Immunoglobulins-special protein produced by plasma cells (Bcells) that will recognize and bind to its specific epitope of an antigen via its antigen binding sitesAmy Warenda Czura, Ph.D.6SCCC BIO244 Chapter 17 Lecture Slides-antibodies recognize and bind to specific shape of antigen’s epitope-antibodies have great specificity-affinity = strength of bond between antigen and antibody-each has minimum of 2 antigen binding sites:both recognize same epitope (antigen)Antibody Molecule Structure: (on handout)Amy Warenda Czura, Ph.D.7SCCC BIO244 Chapter 17 Lecture SlidesIgG antibodies• Pentamer• 5-10% of serum antibodies• Produced only on first exposure• In blood, lymph, on B cells• Fix complement, agglutinates antigensIgM antibodies• Dimer• 10-15% of serum antibodies• In secretions• Mucosal protectionIgA antibodies• Monomer• 0.2% of serum antibodies• Surface receptor on B cells• Initiate humoral immune response by B cellsIgD antibodies• Monomer• 0.002% of serum antibodies• Surface receptor on mast cells and basophils• Inflammation, allergic reactions;lysis of parasitic wormsIgE antibodiesClasses of Antibodies/ImmunoglobulinsIgGIgMIgAIgDIgE(on handout)• Monomer• 80% of serum antibodies• Produced on second+ exposures• In blood, lymph• Can enter tissues, cross placenta• Fix complement, enhance phagocytosis,neutralize toxins & viruses, protects fetus& newborn, antiserumAmy Warenda Czura, Ph.D.8SCCC BIO244 Chapter 17 Lecture SlidesB cells and Humoral Immunity-B cells produce antibodies = humoral / antibody-mediated immunity-B cells arise from stem cells in bone marrow-when mature, migrate to lymphoid tissue-wait to recognize and bind to antigen to be stimulated to produce antibodiesActivation of B cells by clonal selection:-each B cells produces only one antibody against one antigen/epitope-recognizes antigen/epitope via IgD receptoron cell surface-when activated it will divide to produce clones(on handout)Amy Warenda Czura, Ph.D.9SCCC BIO244 Chapter 17 Lecture SlidesActivation and Clonal Selection of B cellsT-independent Antigen(Epitope tends to be polysaccharide, producesweaker immune response than T-dependent Antigen)1. IgD antibody receptor on B cell binds its specific antigen/epitope2. B cell is activated and undergoes clonal selection: the B cell proliferates and differentiatesinto two types of cell populations: Memory B cells and Plasma Cells3. Plasma cells secrete antibodies specific for the original epitope (2000 antibody moleculesper second) for 3-5 days [Time from initial antigen binding to antibodies appearing in theblood is 7-10 days] Antibodies bind to free antigens.4. Upon second exposure to the same antigen/epitope, memory cells bind antigen and are triggered to differentiate into plasma cells and secrete antibodies. [Time from initial antigen binding to antibodies appearing in the blood is 2-5 days]Memory cells = long term immunityAmy Warenda Czura, Ph.D.10SCCC BIO244 Chapter 17 Lecture SlidesPrimary Response:-initial exposure to antigen results in IgM production-peak titer 10-17 days-peak titer of antibodies lowSecondary/Memory Response:-second and subsequent exposure results inIgG production-peak titer 2-7 days-much higher peak titer of antibodiesFunction of Antibodiesantigen-antibody complex = antibody boundby its antigen-binding sites to the epitopeAmy Warenda Czura, Ph.D.11SCCC BIO244 Chapter 17 Lecture SlidesAntigen bound to IgE on Mast cellstriggers histamine release and1.2.3. 4.5.6.MACResults of Antigen-Antibody Binding:(handout)MacrophagesEosinophilsNK cellsAmy Warenda Czura, Ph.D.12SCCC BIO244 Chapter 17 Lecture SlidesT cells and Cell-Mediated Immunity-requires coordinated activity of specializedcells that must