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A daptive I mmune S ystem

A daptive I mmune S ystem. Angela Mitchell BIO422 10/25/10 mitcheam@email.unc.edu. “Jobs” of the Immune System. “Jobs” of the Immune System. Recognize that invaders are present Recognize that these are different than self Recruit more cells/factors to fight invaders Kill the invaders

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A daptive I mmune S ystem

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  1. Adaptive Immune System Angela Mitchell BIO422 10/25/10 mitcheam@email.unc.edu

  2. “Jobs” of the Immune System

  3. “Jobs” of the Immune System • Recognize that invaders are present • Recognize that these are different than self • Recruit more cells/factors to fight invaders • Kill the invaders • Block any toxins produced by the invaders • Learn from past encounters to increase future effectiveness

  4. Overview of Host Response to Pathogens

  5. Time Course of an Immune Response

  6. Levels of the Immune Response

  7. Levels of the Immune Response

  8. Adaptive Responses Are Specific to Individual Molecules • Antigen: the molecule recognized by the response • Each cell can only recognize one antigen

  9. Two Branches of Adaptive Response • Cellular immunity • Main cells are T cells • Used against intracellular pathogens • Humoral immunity • B cells and antibodies • Used against extracellular microbes and toxins

  10. T cell Mediated Immunity Cellular Immune Response

  11. How do T cells recognize antigen? • T cell receptor • Recognizes small parts of proteins “presented” on MHC molecules • MHC is present on antigen presenting cells

  12. Starts with phagocytes recognizing antigen

  13. Antigen is processed and displayed: MHCI

  14. Antigen is processed and displayed: MHCII

  15. Initial recognition by pAPCs • Professional antigen presenting cells • Dendritic cells, macrophages, and B cell • Offer activating signals to T cells—primes for activity

  16. Types of T cells • Cytotoxic T cells: CD8+ T cells • Recognize antigens on MHCI • Releases granules to kills target cells • Helper T cells: CD4+ T cells • Recognize antigens on MHCII • Secrete cytokines to activate other cells • Two types: Th1 and Th2

  17. Cytotoxic T cells (Tc)

  18. Helper T cells (Th) Th1 Cells: activate phagocytes Th2 Cells: activate B cells

  19. Concept Question Cytotoxic T cells are important for defense from… • Bacteria only • Intracellular pathogens • Viruses only • Fungus only • Extracellular pathogens

  20. Concept Question What do helper T cells recognize? • Exogenous peptides on MHCI • Carbohydrates on bacteria cells • Exogenous peptides on MHCII • Endogenous peptides on MHCII • Endogenous peptides on MHCI

  21. B cell Mediated Immunity Humoral Immune Response

  22. B cells Produce Antibodies • Defense from extracellular pathogens and toxins • Recognize antigen in native form

  23. Activation of B cells • B cell receptor (BCR) recognizes antigen • Th2 cells help activation • B cell differentiates to plasma cell • Produces antibodies

  24. Antibody Structure • Immunoglobulins (Ig) • Functions • Neutralize pathogens and toxins • Lead to phagocytosis • Activation of complement

  25. Types of Antibodies

  26. Types of Antibodies

  27. Concept Question B cells recognize _____ with membrane bound_____. • Peptides only MHCs • Whole antigens MHCs • Peptides only Antibodies • Carbohydrates only TLRs • Whole antigens Antibodies

  28. Immunological Memory

  29. Timing of Adaptive Response

  30. Immunological Memory

  31. Secondary Immune Response

  32. Memory Responses • Small populations of B and T cells retained from first exposure • Survive for a long time • Begin faster than first response • Stronger than first response

  33. Immune System Summary

  34. Adaptive Immune System

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