1. Immune system Haixu Tang School of Informatics

2. Human lymphoid organs

3. Lymphocytes are required for adaptive immune responses to foreign antigens

4. Innate immune system helps activate the adaptive immune system

5. The development and activation of T and B cells

6. The clonal selection theory

7. Primary and secondary antibody responses

8. Cellular basis of immunological memory

9. Induction of immunological tolerance

10. B cell activation

11. Innate and adaptive immune responses

12. An antibody molecule

13. Antibody-antigen interactions

14. The hinge region of an antibody molecule

15. A pentameric IgM molecule

16. Antibody-activated phagocytosis

17. There Are Five Classes of Heavy Chains ● IgM, which has μ heavy chains, is always the first class of antibody made by a developing B cell; ● After leaving the bone marrow, the B cell starts to produce cell- surface IgD molecules as well, with the same antigen-binding site as the IgM molecules. ● The major class of immunoglobulin in the blood is IgG, which is a four-chain monomer produced in large quantities during secondary immune responses; ● IgA is the principal class of antibody in secretions, including saliva, tears, milk, and respiratory and intestinal secretions; ● The tail region of IgE molecules, which are four-chain monomers, binds with unusually high affinity (Ka ~ 1010 liters/mole) to yet another class of Fc receptors;

18. Antigen binding to antibody

19. Constant and variable regions

20. The gene of an antibody heavy chain

21. 3D structure of antibody

22. Antigen-binding sites of antibodies

23. DNA is rearranged during B cell development

24. The V-J joining process

25. The human heavy-chain gene- segment pool

26. The four main mechanisms of antibody diversification

27. Antibody gene-pool selection in B cell development

28. The two main classes of adaptive immune responses

29. DNA rearrangement that occurs in class switch recombination

30. T cell responses differ from B cell responses in two crucial ways ● T cells are activated by foreign antigen to proliferate and differentiate into effector cells only when the antigen is displayed on the surface of antigen-presenting cells in peripheral lymphoid organs. Whereas B cells recognize intact antigen, T cells recognize fragments of protein antigens that have been partly degraded inside the antigen- presenting cell. The peptide fragments are then carried to the surface of the presenting cell on special molecules called MHC proteins; ● The second difference is that, once activated, effector T cells act only at short range, either within a secondary lymphoid organ or after they have migrated into a site of infection. They interact directly with another cell in the body, which they either kill or signal in some way. Activated B cells, by contrast, secrete antibodies that can act far away.

31. Two main classes of T cells ● Effector cytotoxic T cells directly kill cells that are infected with a virus or some other intracellular pathogen. ● Effector helper T cells, by contrast, help stimulate the responses of other cellsmainly macrophages, B cells, and cytotoxic T cells

32. T cell receptor heterodimer

33. Activation of a T cell

34. Cytotoxic T cells kill their target cells

35. Differentiation of naïve helper T cells into either TH1 or TH2 effector helper cells

36. Recognition by T cells of foreign peptides bound to MHC proteins

37. Class I and class II MHC proteins

38. Human MHC genes

39. A peptide bound in the groove of a class I MHC protein

40. A peptide bound in the groove of a class II MHC protein

41. The interaction of a T cell receptor with a viral peptide bound to a class I MHC protein

42. CD4 and CD8 co-receptors on the surface of T cells

43. An effector cytotoxic T cell recognizes some aspect of the surface of the host target cell

44. The processing of a viral protein for presentation to cytotoxic T cells

45. The processing of an extracellular protein antigen for presentation to a helper T cell

46. Positive and negative selection in the thymus

47. The two signals that activate a helper T cell

48. The signaling events initiated by the binding of peptide-MHC complexes to T cell receptors

49. The stimulation of T cells by IL-2 in culture

50. The activation of TH1 and TH2 cells

51. Signaling events activated by the binding of antigen to B cell receptors (signal I)

52. The influence of B cell co- receptors on the effectiveness of signal I

53. Comparison of the signals required to activate a helper T cell and a B cell