Immunology Is The Study Of Immunity Adaptive Defense System: Third Line .

Slide 1The Lymphatic System and Body DefensesCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 2Adaptive Defense System: Third Line of Defense Immune response is the immune system’sresponse to a threat Immunology is the study of immunity Antibodies are proteins that protect frompathogensCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 3Adaptive Defense System: Third Line of Defense Three aspects of adaptive defense Antigen specific—recognizes and acts againstparticular foreign substances Systemic—not restricted to the initial infection site Memory—recognizes and mounts a stronger attack onpreviously encountered pathogensCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 4Adaptive Defense System: Third Line of Defense Types of Immunity Humoral immunity antibody-mediated immunity Provided by antibodies present in body fluids Cellular immunity cell-mediated immunity Targets virus-infected cells, cancer cells, and cells offoreign graftsCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 5Adaptive Defense System: Third Line of Defense Antigens (nonself) Any substance capable of exciting the immune systemand provoking an immune response Examples of common antigens Foreign proteins (strongest) Nucleic acids Large carbohydrates Some lipids Pollen grains MicroorganismsCopyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 6Adaptive Defense System: Third Line of Defense Self-antigens Human cells have many surface proteins These along form the major histocomptability complex(MHC) Our immune cells do not attack our own proteins Our cells in another person’s body can trigger animmune response because they are foreign Restricts donors for transplantsCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 7Adaptive Defense System: Third Line of Defense Allergies Delayed hypersensitivity Many small molecules (called haptens orincomplete antigens) are not antigenic, but link upwith our own proteins Poison ivy The immune system may recognize and respond toa protein-hapten combination The immune response is harmful rather thanprotective because it attacks our own cellsCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 8 Allergies Immediate hypersensitivity Non haptan. The antigen itself triggers immuneresponse. Pollen allergies Body has developed antibodies against an irritant Severe reactions can lead to anaphylactic shock Intense severe swelling of tissues Closure of airwaysCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 9Adaptive Defense System: Third Line of Defense Cells of the adaptive defense system Lymphocytes respond to specific antigens B lymphocytes (B cells) T lymphocytes (T cells) Macrophages help lymphocytesCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 10Adaptive Defense System: Third Line of Defense Immunocompetent— cell becomes capable ofresponding to a specific antigen by binding to it Cells of the adaptive defense system Lymphocytes Originate from hemocytoblasts in the redbone marrow B lymphocytes become immunocompetent inthe bone marrow (remember B for Bonemarrow) T lymphocytes become immunocompetent inthe thymus (remember T for Thymus)Copyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 11Lymphocyte Differentiation and ActivationLymphocytes destined to become T cellsmigrate from bone marrow to the thymusand develop immunocompetence there.B cells develop immuno-competence inthe bone marrow.Bone marrowCirculationin bloodImmaturelymphocytesThymusImmunocompetent,but still naive,lymphocytesmigrate via bloodAfter leaving the thymus or bone marrowas naive immunocompetent cells,lymphocytes ―seed‖ the infectedconnective tissues (especially lymphoidtissue in the lymph nodes), where theantigen challenge occurs and thelymphocytes become fully activated.Bone marrowActivated (mature) lymphocytes circulatecontinuously in the bloodstream andlymph, and throughout the lymphoidorgans of the body.Lymph nodesand otherlymphoid tissuesKEY:MatureimmunocompetentB and T cellsrecirculate inblood and lymphSite of lymphocyte originandSites of development ofimmunocompetence as Bor T cells; primary lymphoid organsSite of antigen challenge and finaldifferentiation to mature B and T cellsFigure 12.11Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 12Adaptive Defense System: Third Line of Defense Cells of the adaptive defense system (continued) Macrophages Arise from monocytes Become widely distributed in lymphoidorgans Secrete cytokines (proteins important inthe immune response) Tend to remain fixed in the lymphoidorgansCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 13Humoral (Antibody-Mediated) Immune Response B lymphocytes with specific receptors bind to aspecific antigen The binding event activates the lymphocyte toundergo clonal selection A large number of clones are produced (primaryhumoral response)Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 14Humoral Immune Response Most B cells become plasma cells Produce antibodies to destroy antigens Activity lasts for 4 or 5 days Some B cells become long-lived memory cells(secondary humoral response)Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 15Humoral Immune Response Secondary humoral responses Memory cells are long-lived A second exposure causes a rapid response The secondary response is stronger andlonger lastingCopyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 16Humoral Immune ResponsePrimary Response(initial encounterwith antigen)B lymphoblastsProliferation toform a cloneAntigenAntigen bindingto a receptor on aspecific B cell(lymphocyte)(B cells withnon-complementaryreceptors remaininactive)PlasmacellsMemoryB cellSecretedantibodymoleculesSecondary Response(can be years later)Subsequent challengeby same antigenClone of cellsidentical toancestral cellsPlasmacellsSecretedantibodymoleculesMemoryB cellsFigure 12.12Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 17Humoral Immune ResponsePLAY Humoral ImmunityFigure 12.13Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 18Active Immunity Occurs when B cells encounter antigens andproduce antibodies Active immunity can be Naturally acquired during bacterial and viralinfections Artificially acquired from vaccinesCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 19Passive Immunity Occurs when antibodies are obtained fromsomeone else Conferred naturally from a mother to her fetus(naturally acquired) Conferred artificially from immune serum orgamma globulin (artificially acquired) Immunological memory does not occur Protection provided by ―borrowed antibodies‖Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 20Passive Immunity Monoclonal antibodies Antibodies prepared for clinical testing ordiagnostic services Produced from descendents of a single cellline Examples of uses for monoclonal antibodies Diagnosis of pregnancy Treatment after exposure to hepatitis andrabiesCopyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 21Types of Acquired ImmunityFigure 12.14Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 22Antibodies (Immunoglobulins or Igs) Soluble proteins secreted by B cells (plasmacells) Carried in blood plasma Capable of binding specifically to an antigenCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 23Antibodies (Immunoglobulins or Igs)Figure 12.15aCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 24Antibodies Antibody structure Four amino acid chains linked by disulfidebonds Two identical amino acid chains are linked toform a heavy chain The other two identical chains are light chains Specific antigen-binding sites are presentCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 25Antibody StructureFigure 12.15bCopyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 26Antibodies Antibody classes Antibodies of each class have slightlydifferent roles Five major immunoglobulin classes (MADGE) IgM—can fix complement IgA—found mainly in mucus IgD—important in activation of B cell IgG—can cross the placental barrier andfix complement IgE—involved in allergiesCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 27Immunoglobin ClassesTable 12.2Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 28Antibodies Antibody function Antibodies inactivate antigens in a number ofways Complement fixation Neutralization Agglutination PrecipitationCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 29Antibody FunctionPLAY AntibodiesFigure 12.16Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 30Cellular (Cell-Mediated) Immune Response Antigens must be presented by macrophages toan immunocompetent T cell (antigenpresentation) T cells must recognize nonself and self (doublerecognition) After antigen binding, clones form as with B cells,but different classes of cells are producedCopyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 31Cellular (Cell-Mediated) Immune ResponseFigure 12.17Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 32Cellular (Cell-Mediated) Immune Response T cell clones Cytotoxic (killer) T cells Specialize in killing infected cells Insert a toxic chemical (perforin) Helper T cells Recruit other cells to fight the invaders Interact directly with B cellsCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 33Cellular (Cell-Mediated) Immune ResponsePLAY Cytotoxic T CellsPLAY Helper T CellsFigure 12.18Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 34Cellular (Cell-Mediated) Immune Response T cell clones (continued) Regulatory T cells Release chemicals to suppress the activityof T and B cells Stop the immune response to preventuncontrolled activity A few members of each clone are memorycellsCopyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 35Functions of Cells and MoleculesInvolved in ImmunityTable 12.3 (1 of 2)Copyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Slide 36Functions of Cells and MoleculesInvolved in ImmunityTable 12.3 (2 of 2)Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 37Summary of Adaptive Immune ResponseFigure 12.19Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 38Summary of Adaptive Immune ResponseFigure 12.19 (1 of 2)Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 39Summary of Adaptive Immune ResponseFigure 12.19 (2 of 2)Copyright 2009 Pearson Education, Inc., publishing as Benjamin CummingsSlide 40Organ Transplants and Rejection Major types of grafts Autografts—tissue transplanted from one siteto another on the same person Isografts—tissue grafts from an identicalperson (identical twin) Allografts—tissue taken from an unrelatedperson Xenografts—tissue taken from a differentanimal speciesCopyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings