1. Specific Defenses The Immune System

2. Definitions Innate (nonspecific)Defenses against any pathogen Innate (nonspecific)Defenses against any pathogen ImmunitySpecific antibody and lymphocyte response to an antigen ImmunitySpecific antibody and lymphocyte response to an antigen Antigen (Ag)A substances that causes the body to produce specific Antigen (Ag)A substances that causes the body to produce specific antibodies or sensitized T cells antibodies or sensitized T cells Antibody (Ab)Proteins made in response to an antigen Antibody (Ab)Proteins made in response to an antigen

3. Terminology SerologyStudy of reactions between antibodies and antigens SerologyStudy of reactions between antibodies and antigens AntiserumGeneric term for serum because it contains Ab AntiserumGeneric term for serum because it contains Ab GlobulinsSerum proteins GlobulinsSerum proteins Gamma (  ) globulinSerum fraction containing Ab Gamma (  ) globulinSerum fraction containing Ab

4. Serum Proteins Figure 17.2

5. Immunity Types Acquired immunityDeveloped during an individual's lifetime Acquired immunityDeveloped during an individual's lifetime Humoral immunityInvolves Ab produced by B cells Humoral immunityInvolves Ab produced by B cells Cell-mediated immunityInvolves T cells Cell-mediated immunityInvolves T cells

6. Acquired Immunity Naturally acquired active immunity Naturally acquired active immunity Resulting from infection Resulting from infection Naturally acquired passive immunity Naturally acquired passive immunity Transplacental or via colostrum Transplacental or via colostrum Artificially acquired active immunity Artificially acquired active immunity Injection of Ag (vaccination) Injection of Ag (vaccination) Artificially acquired passive immunity Artificially acquired passive immunity Injection of Ab Injection of Ab

7. Antigenic Determinants Antibodies recognize and react with antigenic determinants or epitopes. Antibodies recognize and react with antigenic determinants or epitopes. Figure 17.3

8. Haptens Figure 17.4

9. Antibody Structure Figure 17.5a-c

10. Monomer Monomer 80% of serum antibodies 80% of serum antibodies Fix complement Fix complement In blood, lymph, intestine In blood, lymph, intestine Cross placenta Cross placenta Enhance phagocytosis; neutralize toxins & viruses; protects fetus & newborn Enhance phagocytosis; neutralize toxins & viruses; protects fetus & newborn Half-life = 23 days Half-life = 23 days IgG antibodies

11. Pentamer Pentamer 5-10% of serum antibodies 5-10% of serum antibodies Fix complement Fix complement In blood, lymph, on B cells In blood, lymph, on B cells Agglutinates microbes; first Ab produced in response to infection Agglutinates microbes; first Ab produced in response to infection Half-life = 5 days Half-life = 5 days IgM antibodies

12. Monomer Monomer 0.002% of serum antibodies 0.002% of serum antibodies On mast cells and basophils, in blood On mast cells and basophils, in blood Allergic reactions; lysis of parasitic worms Allergic reactions; lysis of parasitic worms Half-life = 2 days Half-life = 2 days IgE antibodies

13. Clonal Selection Figure 17.8

14. Bone marrow gives rise to B cells. Bone marrow gives rise to B cells. Mature B cells migrate to lymphoid organs. Mature B cells migrate to lymphoid organs. A mature B cells recognizes epitopes. A mature B cells recognizes epitopes. Clonal Selection

15. Self-tolerance Body doesn't make Ab against self Body doesn't make Ab against self Clonal deletion Clonal deletion The process of destroying B and T cells that react to self antigens The process of destroying B and T cells that react to self antigens

16. The Results of Ag-Ab Binding Figure 17.9

17. Antibody titer: Is the amount of Ab in serum Is the amount of Ab in serum Figure 17.10

18. Monoclonal Antibodies Hybridomas are produced by fusing a cancer cell with an Ab-secreting plasma cells 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) The hybridoma cell culture is immortal and produces monoclonal Abs (Mabs) Immunotoxins: Mabs conjugated with a toxin to target cancer cells Immunotoxins: Mabs conjugated with a toxin to target cancer cells Chimeric Mabs:Genetically modified mice that produce Ab with a human constant region 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 Humanized Mabs: Mabs that are mostly human, except for mouse antigen-binding

19. Monoclonal Antibodies Figure 17.11

20. Interleukin-1Stimulates T H cells Interleukin-1Stimulates T H cells Interleukin-2Activates T H, B, T C, and NK cells Interleukin-2Activates T H, B, T C, and NK cells Interleukin-12Differentiation of CD4 cells Interleukin-12Differentiation of CD4 cells  -InterferonIncrease activity of macrophages  -InterferonIncrease activity of macrophages ChemokinesCause leukocytes to move to an infection ChemokinesCause leukocytes to move to an infection Immune system cells communicate via cytokines

21. Specialized lymphocytes, mostly T cells, respond to intracellular Ags Specialized lymphocytes, mostly T cells, respond to intracellular Ags After differentiating in the thymus, T cells migrate to lymphoid tissue After differentiating in the thymus, T cells migrate to lymphoid tissue T cells differentiate into effector T cells when stimulated by an Ag T cells differentiate into effector T cells when stimulated by an Ag Some effector T cells become memory cells Some effector T cells become memory cells Cell-Mediated Immunity

22. M (microfold) cells in M (microfold) cells in Peyer's patches which contains Peyer's patches which contains Dendritic cells which are antigen- presenting cells and Dendritic cells which are antigen- presenting cells and T cells T cells Pathogens entering the gastrointestinal or respiratory tracts pass through:

23. Dendritic cells present antigens Figure 17.12

24. Helper T Cells (CD4, T H ) Helper T Cells (CD4, T H ) T H 1Activate cells related to cell-mediated immunity T H 1Activate cells related to cell-mediated immunity T H 2Activate B cells to produce eosinophils, IgM, and IgE T H 2Activate B cells to produce eosinophils, IgM, and IgE Cytotoxic T Cells (CD8, T C ) Cytotoxic T Cells (CD8, T C ) Destroy target cells with perforin Destroy target cells with perforin T Cells

25. Helper T Cells Figure 17.13

26. Cell-mediated Cytotoxicity Figure 17.14

27. Nonspecific Cells Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines Natural killer cells: Lymphocytes that destroy virus-infected cells, tumor Natural killer cells: Lymphocytes that destroy virus-infected cells, tumor Figure 17.15

28. T-independent Antigens Figure 17.16

29. Antibody-Dependent Cell- Mediated Cytotoxicity Figure 17.18