1. Chapter 15:Adaptive Immune Response

2. General Characteristics Involves specialized WBC’s known as lymphocytes Response is highly specific, evolves throughout an organisms life-time Response generates memory Can discriminate between HEALTHY self and non-self OR between HEALTHY self and DAMAGED self

3. The Adaptive Immune Response Primary response Secondary response Humoral immunity: – B cells, plasma cells, antibodies: target extracellular pathogens Cell-mediated immunity – T cells, dendritic cells – antigen is inside a cell

4. Overview of the Adaptive Immune Response

5. Anatomy of the Lymphoid System Lymphatic Vessels Secondary lymphoid Organs Primary Lymphoid Organs

6. Lymphocytes are responsible for the specific immune response

7. What promotes an immune response? Antigens – Usually proteins or polysaccharides – Foreign substance with MW of 10,000 daltons – Examples of microbial antigens: bacterial capsules, cell walls, flagella, toxins of bacteria

8. Antibodies bind antigens

9. Some molecules are not recognized as antigens until bound to another

10. How are antigens recognized? Self markers also known as MHC markers MHC (major histocompatibility complex) MHC Class I-produced by all body cells MHC Class II-produced by B cells, T cells, and antigen presenting cells

11. Structure of an antibody

12. 5 classes of antibodies IgM Produced 1 st Complement activation Primary function = neutralize pathogens in the bloodstream 10 antigen binding sites

13. 5 classes of antibodies IgG Longest half-life Small enough to cross endothelium bbb, some types of placenta Main antibody produced in 2° immune reactions

14. 5 classes of antibodies IgA Monomeric & dimeric Dimer = secretory IgA sIgA = most abundant Ab Secreted across mucosal surfaces in mucus & many other secretions (tears, saliva, milk) Binding → neutralize toxins, block viral and bacterial attachment

15. 5 classes of antibodies IgE Bound to Fc region of mast cells and basophils Cross-linking of IgE by antigen → degranulation

16. 5 classes of antibodies IgD Activation of basophils & mast cells Activation of B cells Highly conserved Functions minimally elucidated

17. What can happen when antibody binds antigen?

18. How are B cells activated?

19. B cell activation by Helper T cell

20. Primary and secondary response to antigen Affinity maturation Class switching IgM → IgG IgM → IgA Memory B cells+ memory helper T cells: long lived (years)

21. Helper T cells help activate other immune cells

22. T cells Have own T cell receptor (TCR) Do not make antibodies Must recognize MHC markers which “present” antigen

23. MHC markers

24. Cytotoxic T cells recognize MHC Class I markers

25. Helper T cells recognize MHC Class II

26. Dendritic cells can activate T cells

27. Cytotoxic T cells

29. Cytotoxic T cells identify infected body cells

30. Helper T cells activate macrophages

31. Helper T cells activate B cells

32. T cell-independent antigens

33. Antibody-dependent cell-mediated cytotoxicity