1. Immunity

2. Impacts, Issues Frankie’s Last Wish
Infection with a common, sexually transmitted virus (HPV) causes most cervical cancers – including the one that killed Frankie McCullogh

3. A. Integrated Responses to Threats
Immunity - the capacity to resist and combat infection by pathogens such as viruses, bacteria, and fungi
Proteins in eukaryotic cell membranes have unique patterns (antigens) that the body recognizes as self & cells of multicelled eukaryotes have receptors that recognize nonself cues (anitgens) on or in pathogens, and trigger defense responses

4. B. Three Lines of Defense
1. Physical, chemical, and mechanical barriers - keep pathogens outside the body

5. Chemical Weapons of Immunity

6. Vertebrate Surface Barriers

7. B. Three Lines of Defense
1. Physical, chemical, and mechanical barriers - keep pathogens outside the body
2. Innate immunity
General responses destroy invaders inside the body before they become established
Complement: Proteins that destroy microorganisms or flag them for phagocytosis

8. Animation: Innate defenses
videos_animations/innate_defenses_m.html

9. B. Three Lines of Defense
1. Physical, chemical, and mechanical barriers - keep pathogens outside the body
2. Innate immunity
General responses destroy invaders inside the body before they become established
Complement: Proteins that destroy microorganisms or flag them for phagocytosis
3. Adaptive immunity
system of defenses that specifically targets billions of different antigens an individual may encounter during its lifetime
Huge populations of white blood cells form to target and remember a specific antigen

10. Comparing Innate and Active Immunity

11. White Blood Cells

12. C. Innate Immune Responses
Innate immune mechanisms nonspecifically eliminate pathogens that invade internal tissues before they become established
Phagocytes
Complement
Inflammation
Fever

13. 1. Phagocytes (Macrophages)
Large phagocytes that patrol interstitial fluid and engulf and digest pathogens
Secrete cytokines when receptors bind to antigen
Cytokines attract more macrophages, neutrophils, and dendritic cells to infection site

14. Complement proteins become activated when they encounter antigen
Cascading enzyme reactions concentrate activated complement at infection site
Complement attracts phagocytes to infection site and tags pathogens for destruction
Forms attack complexes that puncture bacteria
Helps mediate active immunity

15. Complement Attack Complexes

16. Animation: Complement proteins
videos_animations/membrane_attack.html

17. Inflammation
A local response to tissue damage characterized by redness, warmth, swelling and pain, triggered by activated complement and cytokines
Mast cells release histamine, increasing capillary permeability
Phagocytes and plasma proteins leak out, attack invaders, form clots, and clean up debris

18. A Bacteria invade a tissue and release toxins or metabolic products that damage tissue.
D Complement proteins attack bacteria. Clotting factors also wall off inflamed area.
E Neutrophils and macrophages engulf invaders and debris. Macrophage secretions kill bacteria, attract more lymphocytes, and initiate fever.
B Mast cells in tissue release histamine, which widens arterioles (causing redness and warmth) and increases capillary permeability.
C Fluid and plasma proteins leak out of capillaries; localized edema (tissue swelling) and pain result.
Figure 38.8
Inflammation in response to bacterial infection. Above, in this example, white blood cells and plasma proteins enter a damaged tissue. Right, the micrograph shows a phagocyte squeezing through a blood vessel wall.
Stepped Art
Fig. 38-8, p. 665

19. Fever
A temporary rise in body temperature – above the normal 37°C (98.6°F) – that often occurs in response to infection
Cytokines stimulate brain cells to release prostaglandins, which act on the hypothalamus
Fever enhances the immune response by speeding up metabolism and phagocyte activity
Fever over 40.6°C (105°F) can be dangerous

20. D. Overview of Adaptive Immunity
Vertebrate adaptive immunity adapts to different antigens it encounters during its lifetime
Lymphocytes and phagocytes interact to effect four defining characteristics: Self/nonself recognition, specificity, diversity, and memory

21. 3. First Step – The Antigen Alert
Once a B or T cell recognizes and binds to a specific antigen, it begins to divide by mitosis - all descendent cells recognize the same antigen
T cells do not recognize an antigen unless it is presented by an antigen-presenting cell - macrophages, B cells, and dendritic cells digest particles and display antigen-MHC complexes

22. c. Cell Types
Effector cells - differentiated lymphocytes (B and T cells) that act at once to fight infection
Memory cells - long-lived B and T cells reserved for future encounters with the same antigen

23. cell engulfs an antigen-bearing particle
antigen–MHC complexes become displayed on cell surface
endocytic vesicle forms
MHC markers bind fragments
of particle
particle is digested into bits
lysosome fuses with endocytic vesicle
Figure 38.9
Antigen processing. (a) A macrophage ingests a foreign cell. (b) From encounter to display, what happens when a B cell, macrophage, or dendritic cell engulfs an antigenic particle—in this case, a bacterium. These cells engulf, process, and then display antigen bound to MHC markers. The displayed antigen is presented to T cells.
Stepped Art
Fig. 38-9b, p. 666

24. 4. Two Arms of Adaptive Immunity
Antibody-mediated immune response - B cells produce antibodies that bind to specific antigen particles in blood or interstitial fluid
Cell-mediated immune response - Cytotoxic T cells and NK cells detect and destroy infected or altered body cells

25. Interactions Between Antibody-Mediated and Cell-Mediated Responses

26. 5. Intercepting and Clearing Out Antigen
After engulfing antigen-bearing particles, dendritic cells or macrophages migrate to lymph nodes, where T cells bind and initiate responses
During an infection, lymph nodes swell due to accumulation of T cells
Antibody-antigen complexes bound by complement are cleared by the liver and spleen

27. The Lymphatic System

28. E. Antibodies and Other Antigen Receptors
Antigen receptors on B and T cells have the potential to recognize billions of different antigens
Antibody
Y-shaped antigen receptor (protein), made only by B cells, that binds only to the antigen that prompted its synthesis
Activates complement, facilitates phagocytosis, or neutralizes pathogens or toxins

29. Antibody Structure

30. 3. Making Antigen Receptors
Genes that encode antigen receptors occur in several segments on different chromosomes
Different versions are randomly spliced together during B or T cell differentiation, producing about 2.5 billion different combinations
T cells mature in the thymus, which stimulates production of MHC and T cell receptors

31. Antigen Receptor Diversity

32. F. The Antibody-Mediated Immune Response
Antigen activates naïve B cells and dendritic cells
Naïve T cell binds to APC and differentiates into effector and memory helper T cells
Helper T cells bind antigen-MHC complexes on activated B cell and secrete cytokines
B cell differentiates into effector B cells, which produce antibodies targeting a specific antigen, and memory B cells

33. antigen- presenting dendritic cellB
bacterium
antigen- presenting dendritic cell
B The dendritic cell engulfs the same kind of bacterium that the B cell encountered. A
naive B cell
B cell
complement
A The B cell receptors on a naïve B cell bind to a specific antigen on the surface of a bacterium
C The antigen-MHC complexes on the antigen-presenting cell are recognized by antigen receptors on a naïve T cell.
naive T cell
effector helper T cell
memory helper T cell C
D cytokines
D Antigen receptors of one of the effector helper T cells bind antigen-MHC complexes on the B cell. E
memory B cell
effector B cell
E The cytokines induce the B cell to divide, giving rise to many identical B cells. F
F The effector B cells begin making and secreting huge numbers of IgA, IgG, or IgE.
Figure 38.14
Example of an antibody-mediated immune response.
Stepped Art
Fig , p. 670

34. 5. Clonal Selection and Memory Cells
Only B cells with receptors that bind antigen divide (clone) and differentiate into effector and memory B cells
First exposure (primary response) produces memory B and T cells; secondary response is stronger and faster

35. Clonal Selection and Memory Cells

36. Primary and Secondary Immune Response

37. G. The Cell-Mediated Response
Dendritic cell ingests altered body cell, displays antigen-MHC complexes, migrates to lymph node
Naïve helper T and cytotoxic T cells bind to APC
Activated helper T divides and differentiates into memory and effector cells; cytokines signal division of activated cytotoxic T cells
Cytotoxic T cells circulate and touch-kill altered body cells

38. A A dendritic cell engulfs a virus-infected cell.
antigen- presenting dendritic
cell
A A dendritic cell engulfs a virus-infected cell. B
effector helper T cell
memory helper T cell
B Receptors on a naïve helper T cell bind to antigen-MHC complexes on the dendritic cell.
naive helper T cell
naive cytotoxic T cell C
activated cytotoxic
T cell
C Receptors on a naïve cytotoxic T cell bind to the antigen-MHC complexes on the surface of the dendritic cell. D
cytokines
memory cytotoxic T cell
effector cytotoxic T cell
D The activated cytotoxic T cell recognizes cytokines secreted by the effector helper T cells as signals to divide.
Figure 38.17
Example of a primary cell-mediated immune response.
Figure It Out: What do the large red spots represent?
Answer: Viruses E
E The new cytotoxic T cells circulate through the body.
Stepped Art
Fig , p. 672

39. Cytotoxic T Cells

40. Animation: Cell mediated response
videos_animations/cell_mediated_vid.html

41. 5. Natural Killer Cells
Cytokines secreted by helper T cells also stimulate natural killer (NK) cell division
Unlike cytotoxic T cells, NK cells can kill infected cells that are missing all or part of their MHC markers

42. H. Allergies
An immune response to a typically harmless substance (allergen)
First exposure stimulates production of IgE, which becomes anchored to mast cells and basophil
Later exposure stimulates secretion of histamine and cytokines that initiate inflammation
Anaphylactic shock is a severe and potentially fatal allergic reaction

43. Allergies: Annoying or Life-Threatening

44. ABC video: Food Allergy Increase
videos_animations/Food_Allergy_Increase.html

45. I. Vaccines
Immunization - the administration of an antigen-bearing vaccine designed to elicit immunity to a specific disease
Vaccine (active immunization) - a preparation containing an antigen that elicits a primary immune response
Passive immunization - administration of antibodies; no immune response

46. Smallpox Vaccine
Edward Jenner created the first vaccine against smallpox, which has now been eradicated

47. Recommended Immunizations

48. J. Immunity Gone Wrong
Misdirected or compromised immunity is sometimes the result of mutation or environmental factors
The outcome is often severe or lethal

49. 1. Autoimmune Disorders
Sometimes lymphocytes and antibodies fail to discriminate between self and nonself
Autoimmune response
An immune response that is misdirected against the person’s own tissues
Rheumatoid arthritis, Graves’ disease, multiple sclerosis

50. 2. Immunodeficiency
In immunodeficiency, the immune response is insufficient to protect a person from disease
Primary immune deficiencies are present at birth - SCIDs, ADA
Secondary immune deficiency results from exposure to an outside agent, such as a virus - AIDS

51. 3. Gene Therapy
Primary immunodeficiency is the result of mutation; Cindy Cutshwall was successfully treated for ADA, a type of severe combined immunodeficiency (SCID), using gene therapy

52. Video: Gene therapy
videos_animations/gene_therapy.html

53. K. AIDS Revisited—Immunity Lost
Acquired immune deficiency syndrome (AIDS)
A group of disorders resulting from a failure of the immune system due to HIV infection
Includes rare cancers and infections caused by normally harmless microorganisms
Human immunodeficiency virus (HIV) - a retrovirus that attacks specific cells of the immune system, including helper T cells

54. T Cells and AIDS

55. Global HIV and AIDS Cases

56. 3. Transmission and Treatment
Common modes of HIV transmission - unprotected sex, mother to child, shared syringes
HIV testing - antibodies are found in blood, saliva or urine
Drugs - there is no cure; protease inhibitors and reverse transcriptase inhibitors can slow its progress

57. 4. Prevention
Vaccines - experimental vaccines are mostly ineffective or risky; the virus’ high mutation rate is an obstacle
Education - the best option for preventing the spread of HIV is teaching people how to avoid being infected

58. 5. The Global AIDS Program
The global battle continues; researchers are using several strategies to develop an HIV vaccine

59. Video: HPV vaccine
videos_animations/csHPV_Vaccine.html