2. VariolationLady Montagu

3. Edward JennerSmallpox

4. Pathogens (such as bacteria, fungi, and viruses) INNATE IMMUNITY (all animals) Rapid response Recognition of traits shared by broad ranges of pathogens, using a small set of receptors Recognition of traits specific to particular pathogens, using a vast array of receptors Slower response Barrier defenses: Skin Mucous membranes Secretions Internal defenses: Phagocytic cells Natural killer cells Antimicrobial proteins Inflammatory response Humoral response: Antibodies defend against infection in body fluids. Cell-mediated response: Cytotoxic cells defend against infection in body cells. ADAPTIVE IMMUNITY (vertebrates only) Figure 43.2

5. Figure 43.3 Pathogen PHAGOCYTIC CELL Vacuole Lysosome containing enzymes

6. Thymus Peyer’s patches (small intestine) Appendix (cecum) Adenoid Tonsils Lymphatic vessels Spleen Lymph nodes Lymph node Blood capillary Interstitial fluid Tissue cells Lymphatic vessel Masses of defensive cells Figure 43.7

9. Figure 43.8-1 Pathogen Splinter Mast cell Macro- phage Capillary Red blood cells Neutrophil Signaling molecules

10. Figure 43.8-2 Pathogen Splinter Mast cell Macro- phage Capillary Red blood cells Neutrophil Signaling molecules Movement of fluid

11. Figure 43.8-3 Pathogen Splinter Mast cell Macro- phage Capillary Red blood cells Neutrophil Signaling molecules Movement of fluid Phagocytosis

12. Cytoplasm of B cell Antigen- binding site B cell antigen receptor B cell Light chain Disulfide bridge Antigen- binding site Variable regions Constant regions Transmembrane region Heavy chains Plasma membrane C C C C V V V V Figure 43.9

13. Figure 43.10a Antibody Antigen receptor B cell Antigen Epitope Pathogen (a) B cell antigen receptors and antibodies

14. Antigen Antigen receptor Antibody Plasma cells Memory cells B cells that differ in antigen specificity Figure 43.14

17. Primary immune response to antigen A produces antibodies to A. Secondary immune response to antigen A produces antibodies to A; primary immune response to antigen B produces antibodies to B. Exposure to antigen A Exposure to antigens A and B Time (days) Antibody concentration (arbitrary units) 10 4 10 3 10 2 10 1 10 0 0 7 14 2128 35 42 49 56 Antibodies to A Antibodies to B Figure 43.15

18. Humoral (antibody-mediated) immune response Cell-mediated immune response Antigen (1st exposure) Engulfed by Antigen- presenting cell Helper T cell Memory helper T cells Antigen (2nd exposure) B cell Plasma cells Secreted antibodies Defend against extracellular pathogens Memory B cells Memory cytotoxic T cells Active cytotoxic T cells Defend against intracellular pathogens and cancer Cytotoxic T cell Key Stimulates Gives rise to           Figure 43.20

19. Figure 43.22 IgE Allergen Histamine Granule Mast cell

21. Latency AIDS Helper T cell concentration Years after untreated infection Helper T cell concentration (in blood (cells/mm 3 ) Relative anti-HIV antibody concentration Relative HIV concentration 800 600 400 200 0 0 12 3 456 78 9 10 Figure 43.25