Adaptive Immunity

1. What two defining features characterize adaptive immunity?

Answer: Specificity and memory

2. Which immune cells are primarily responsible for adaptive immunity?

Answer: B cells and T cells

3. Where do B cells and T cells mature?

Answer: B cells mature in bone marrow; T cells mature in the thymus

4. After maturation, where do B and T cells migrate?

Answer: Spleen and lymph nodes

5. What is the primary function of the lymphatic system in adaptive immunity?

Answer: Transport lymphocytes and filter pathogens

6. What happens to microbes that enter a lymph node?

Answer: They are trapped and destroyed by macrophages

7. What type of pathogens are targeted by humoral immunity?

Answer: Extracellular pathogens

8. What type of pathogens are targeted by cell-mediated immunity?

Answer: Intracellular pathogens

9. Which stem cell type gives rise to B cells and T cells?

Answer: Lymphoid stem cell

10. What does immunology study?

Answer: Host defenses against pathogens

11. What is an antigen?

Answer: A molecule that induces an immune response

12. What is an epitope?

Answer: The specific part of an antigen recognized by antibodies or T cells

13. Do antibodies bind entire antigens or epitopes?

Answer: Epitopes

14. What is the difference between monoclonal and polyclonal antibodies?

Answer: Monoclonal bind one epitope; polyclonal bind multiple epitopes

15. What is the basic structure of an antibody?

Answer: Two heavy chains and two light chains

16. What is the function of the Fab region?

Answer: Antigen binding

17. What is the function of the Fc region?

Answer: Binding to complement and immune cells

18. Which antibody class is most abundant in blood and crosses the placenta?

Answer: IgG

19. Which antibody appears first during a primary immune response?

Answer: IgM

20. Which antibody class is involved in allergies and parasitic infections?

Answer: IgE

21. What is the function of MHC molecules?

Answer: Present antigens on cell surfaces

22. Which cells express MHC I molecules?

Answer: All nucleated cells

23. Which cells express MHC II molecules?

Answer: Antigen-presenting cells

24. Which T cells recognize MHC II?

Answer: Helper T cells

25. Which T cells recognize MHC I?

Answer: Cytotoxic T cells

26. What are the steps of antigen presentation by APCs?

Answer: Ingestion → digestion → MHC binding → presentation

27. What causes activation of a helper T cell?

Answer: Binding to MHC II + antigen on an APC

28. What is the role of cytokines released by helper T cells?

Answer: Activate B cells and T cells

29. What happens when a cytotoxic T cell encounters an infected cell?

Answer: It releases toxic proteins that kill the cell

30. What are superantigens?

Answer: Toxins that cause uncontrolled T-cell activation

31. What activates a B cell?

Answer: Antigen binding plus helper T-cell signals

32. What two cell types can activated B cells become?

Answer: Plasma cells and memory B cells

33. What is opsonization?

Answer: Antibody coating of pathogens to enhance phagocytosis

34. How do antibodies activate complement?

Answer: Complement proteins bind antibody-coated bacteria

35. What is neutralization?

Answer: Antibodies block pathogen or toxin binding to host cells

36. What is agglutination?

Answer: Antibody-mediated clumping of pathogens

37. What are the four ways adaptive immunity can be acquired?

Answer: Natural active, natural passive, artificial active, artificial passive

38. What is artificial active immunity?

Answer: Immunity produced by vaccination

39. What is artificial passive immunity?

Answer: Administration of pre-made antibodies

40. What is a toxoid vaccine?

Answer: An inactivated toxin used to stimulate immunity