1. The body’s defenses

2. Reading: Ch. 43; Keywords Lines of defense Lymphatic system Inflammation Features of immune system Memory B-cells Primary and secondary immune responses Antibody Antigen Agglutination macrophage lymphocyte Phagocytosis Complement system Humoral immunity Cell-mediated immunity B cell Helper T cell Cytotoxic T cell

3. Overview

4. Non-specific First line –Skin –Mucous membranes –Secretions of skin and mucous membranes Second line –Phagocytic white blood cells –Anti-microbial proteins –Inflammatory response

5. Second line of defense - macrophage

6. Inflamation

9. Focus on immune system (3rd line of defense) Protects body against specific invaders

10. Key features Specificity Diversity Memory Self/Nonself Recognition

11. First the major players: Lymphocytes

12. The lymphatic system

13. Two types of immune responses Humoral Cell-mediated

14. Key features Specificity Diversity Memory Self/Nonself Recognition Humoral immunity

15. Humoral immunity: B cells and clonal selection

16. There are a variety of B cells

17. One B cell becomes activated and proliferates

18. Some B cells become plasma cells that secrete antibodies

20. Some B cells become memory cells

22. Memory cells function in secondary immune response Primary immune response - first exposure Secondary immune response - second exposure

23. Primary and secondary immune responses

24. Summary Lag in primary response due to proliferation from a single clone Secondary (2°) response is from multiple memory cells 2° response has less of a lag and is stronger

25. What do antibodies do?

26. Inactivate antigens

27. Neutralization

28. Agglutination of antigen bearing particles

29. Precipitation of soluble antigens

30. Inactivate antigens Neutralization Agglutination Precipitation

31. These mechanisms enhance phagocytosis

32. Antibodies inactivate antigens Neutralization of invaders Agglutination Precipitation of soluble antigens The above enhance phagocytosis One final mechanism: Complement system

33. Complement system: Step 1 attachment to pathogen

34. Step 2: Recruitment of complement proteins

35. Step 3: Activation

36. Step 4: pore formation

37. Summary Complement proteins interact with antibodies to kill invading cells Binding of antibody is followed by attachment of complement proteins Protein complex becomes activated Pore is formed in pathogen’s membrane Goodbye pathogen

38. Two types of immune responses Humoral Cell-mediated

39. Complicated, involves cellular components Will briefly touch on role of helper T cells

40. Recall that T cells are the other type of lymphocyte

41. Cell-mediated response happens at the same time

42. Macrophage engulfs invader

43. Antigens from invader are presented on macrophage cell surface

44. Helper T cells are recruited

45. Helper T cells proliferate and activate cytotoxic T cells and B cells

46. T cells infected with HIV