1. Adaptive immunity How can the immune system recognize so many different (previously unseen) insults? How does the immune system learn? How do B cells produce antibodies?

2. Antibody production after immunization

3. Irradiation prevents immune response

4. Which cells can restore the immune response?

5. Origins of lymphocytes

6. B cells T C (Cytotoxic T cells) T H (Helper T cells) Also function in immune system

7. Origins of lymphocytes B cell activation and differentiation

8. Origins of lymphocytes T cell activation

9. Antibody protein structure

10. B cell activation Each naïve B cell makes a single type of antibody with a unique binding specificity Upon activation the naïve B cell proliferates and produces progeny that secrete that antibody

11. Antibody production after immunization

12. Clonal selection

13. Primary response Secondary response

14. Antibody action: Activation of Complement Adaptive immunity (Innate immunity)

15. Antibody action: Action of Complement

16. Antibody action: IgG-mediated phagocytosis

17. Antibody action: IgA is secreted

18. Antibody action: IgE stimulates histamine production

19. Antibody structure Heavy chain constant region determines antibody class N C N C

20. B cell development

21. Heavy chain gene rearrangement

22. Human heavy chain gene-segment pool 51 x 27 x 6 = 8262 possible H chain variable regions 40 x 5 = 200 possible  light chain variable regions 116 possible chain variable regions 2.6 million possible antigen binding sites from gene segment combinations IgM IgD IgG IgE IgA

23. B cell development Light chain gene rearrangement

24. Human  light- chain gene rearrangement

25. Ab gene usage in a pre-B cell (allelic exclusion) (stops gene rearrangements)

26. Clonal selection

27. Memory cells: Somatic hypermutation in V regions Class switching

28. Human heavy chain gene-segment pool 51 x 27 x 6 = 8262 possible H chain variable regions 40 x 5 = 200 possible  light chain variable regions 116 possible chain variable regions 2.6 million possible antigen binding sites from gene segment combinations IgM IgD IgG IgE IgA Rearrangements in memory cells can put a different C region gene segment in register, thereby causing antibody class switching