Understanding Immune Responses in the Human Body

1. Chapter 39: Immunity

2. Fig. 39-1, p.678

3. Fig. 39-2, p.679

4. Three Lines of Defense • Barriers at body surfaces • Nonspecific responses • Immune responses

7. Cells Involved in Immune Responses basophil mast cell eosinophil neutrophil NK cell B lymphocyte T lymphocyte Fig. 39-3a, p.681

8. Cells Involved in Immune Responses dendritic cell macrophage Fig. 39-3b, p.681

9. Fig. 39-4, p.680

10. Barriers at Body Surface • Intact skin and mucous membranes • Lysozyme • Normal bacterial flora • Flushing effect and low pH of urine

12. Barriers Against Infectious Agents Fig. 39-6, p.683

13. Barriers Against Infectious Agents Fig. 39-7, p.683

14. Nonspecific Responses • Lymph nodes trap and kill pathogens • Natural killer cells attack a range of targets • Inflammation

15. Complement System • Plasma proteins that take part in both specific and nonspecific response • Activation of one triggers cascade of reactions that activate others

16. Attack Complexes lipid bilayer of pathogen antibody activated complement bacterial pathogen Cascade Reactions Formation of Attack Complexes Lysis of Target Activation

17. Acute Inflammation • Nonspecific response to foreign invasion, tissue damage, or both • Destroys invaders, removes debris, and prepares area for healing • Characterized by redness, swelling, warmth, and pain

18. Inflammation • Mast cells release histamine • Capillaries dilate and leak • Complement proteins attack bacteria • White cells attack invaders and clean up Figure 39.9Page 685

19. Features of Immune Responses • Self/nonself recognition • Specificity • Diversity • Memory

20. Memory and Effector Cells • When a B or T cell is stimulated to divide, it produces more than one cell type • Memory cells - set aside for future use • Effector cells - engage and destroy the current threat

21. Steps in Immune Response • Recognition of an antigen • Rounds of cell division that form huge populations of lymphocytes • Specialization of lymphocytes into effector and memory cells that have receptors for one kind of antigen

22. Key Components of Immune Response • MHC markers • Antigen-presenting cells • T cells • B cells • Natural killer cells

23. Formation of Antigen-MHC Complex antigen fragments MHC molecule antigen-MHC complex

24. Antigens • “Nonself” markers on foreign agents and altered body cells such as tumors • Trigger division of B and T cells

25. Interactions Between Responses

26. Lymphocyte Battlegrounds • Lymph nodes filter antigens from body fluids • Macrophages, dendritic cells, B and T cells in nodes and spleen mount a defense Figure 39.12Page 687

27. Antibody Structure • Consists of four polypeptide chains • Certain parts of each chain are variable; impart antigen specificity antigen binding site variable region constant region Figure 39.13aPage 688

28. signal reception signal transduction cellular response Antibody-Mediated Immune Response Cell-Mediated Immune Response antigen-presenting cells naive B cells + antigen + complement naive helper T cells activated B cells naive cytotoxic T cells effector helper T cells + memory helper T cells effector B cells + memory B cells effector cytotoxic T cells + memory cytotoxic cells Fig. 39-11, p.687

29. Antibody-Mediated Response • Carried out by B cells • Targets are intracellular pathogens and toxins • Antibodies bind to target and mark it for destruction by phagocytes and complement

30. antigen Clonal Selection • Only the B cell with antigen-receptor that matches antigen is stimulated to divide • Mitosis yields many cells with that receptor clonal population of B cells Figure 39.15Page 690

31. Immunological Memory • Memory cells specific for an antigen are quickly activated to divide upon subsequent exposure to that antigen Primary Immune Response: naïve T or B cell effector cells memory cells Secondary Immune Response: effector cells memory cells Figure 39.15Page 690

32. Primary and Secondary Immune Response Fig. 39-16, p.690

33. Antibody-Mediated Response • B cell becomes antigen-presenting cell • Helper T cell binds to antigen-MHC complex • Interleukins stimulate B cell division and differentiation • Effector cells secrete antibodies antigen naïve B cell MHC molecule antigen- MHC complex helper T cell antigen- presenting B cell interleukins memory B cell antibody effector B cell

34. bacterium dendritic cell complement naive B cell naive T cell antigen-presenting cell cytokines memory helper T cell effector helper T cell B cell effector B cell memory B cell Stepped Art Fig. 39-17, p.691

35. virus particle (red) infecting a body cell (yellow) dendritic cell antigen-MHC complex naive cytotoxic T cell naive helper T cell antigen-presenting cell effector cytotoxic T cell memory cytotoxic T cell effector cytotoxic T cell cytokines memory helper T cell effector helper T cell activated cytotoxic T cell Stepped Art Fig. 39-18, p.692

36. Cell-Mediated Response another macrophage one macrophage • Carried out by T cells • Stimulated by antigen-presenting macrophages • Main target is antigen-presenting body cells (cells with intracellular pathogens) or tumor cells interleukins cytotoxic T cell helper T cell interleukins infected body cell

37. Cytotoxic T Cell cytotoxic T-cell tumor cell Fig. 39-19, p.693

38. Organ Rejection • Cytotoxic T cells can contribute to rejection • They recognize a portion of the donor cell’s MHC complex as self, view a portion as foreign • Treat the combination as an antigen-MHC complex and attack donor cells

39. Immunization • Process that promotes immunity • Active immunization - • Antigen-containing material is injected • Confers long-lasting immunity • Passive - • Purified antibody is injected • Protection is short lived

40. Vaccines Fig. 39-21a, p.694

41. Vaccines RECOMMENDED VACCINES RECOMMENDED AGES Hepatitis B Hepatitis B booster 1 Hepatitis B booster 2 Hepatitis B assessment DTP (Diphtheria; Tetanus; and Pertussin, or whooping cough) DTP booster 1 DTP booster 2 DT HiB (Hemophilus influenzae) HiB booster Polio Polio booster 1 Polio booster 2 MMR (Measles, Mumps, Rubella) MMR booster MMR assessment Pneumococcal Pneumococcal booster 1 Pneumococcal booster 2 Varicella Varicella assessment Hepatitis A (in selected areas Birth–2 months 1–4 months 6–18 months 11–12 years 2, 4, and 6 months 15–18 months 4–6 years 11–16 years 2, 4, and 6 months 12–15 months 2 and 4 months 6–18 months 4–6 years 12–15 months 4–6 years 11–12 years 2, 4, and 6 months 12-15 months 1-18 years 12–18 months 11–12 years 1-12 years Fig. 39-21b, p.694

42. Allergies • Immune reaction to a harmless substance • Genetic predisposition • IgE responds to antigen by binding to mast cells and basophils • These cells secrete the substances that cause symptoms

43. Fig. 39-22a, p.694

44. Fig. 39-22b, p.694

45. AIDS • Combination of disorders that follows infection with HIV • Includes • Yeast (Candida) infections • Pneumocystis pneumonia • Karposi’s sarcoma

46. Global Cases of AIDS/HIV

47. HIV Life Cycle reverse transcriptase viral genes are integrated into the host DNA DNA is transcribed viral RNA enters cell host cell strands of DNA (two) viral RNA reverse transcription of viral RNA viral proteins viral DNA budding core proteins (two layers) integrase

48. T Cell Decline • Release of new viral particles kills the host T cell • The body is constantly making new T cells, but cannot outpace the rate of destruction • As infection proceeds, T cell numbers inevitably decline

49. Effect of T Cell Decline • CD4 helper T cells play a vital role in immune function • They are required for both cell-mediated and antibody-mediated immunity • Infected individual becomes vulnerable to other infections, which eventually result in death