Chapter18CellularImmunity

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Chapter18CellularImmunity
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2009-11-30 01:52:36
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MJC Micro Chapter 18 Cellular Immunity
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Chapter 18 Cellular Immunity
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  1. Cellular Immunity
    • Is due to T cells
    • Eliminates intercellular pathogens
    • Transplanted tissues
    • Cancer
    • Kills infected host cells
    • Helps macrophages kill phagocytosed pathogens
    • Difficult to passively transfer
  2. Types of Effector T Cells
    • CD8 are killer T cells (Tc)
    • CD4 are Helper T cells (Th)
  3. Antigen Presenting Cells
    Present extracellular antigen on MHC II

    Types - Dendritic cells, Macrophages, B cells, CD4 T cells bind and then "help"

    All cells present intracellular antigen on MHC I and CH8 T cells bind, then "kill"
  4. MCH proteins
    • MCH proteins = tissue typing antigens
    • Class 1 MHC is on all nucleated cells - presents antigen on Tc (CD8)

    Class 2 MHC is on professional Antigen Presenting Cells - presents antigen to Th1 and Th2 (CD4)
  5. Where does MHC1 cells load?
    • MHC1 - loads in the golgi
    • Loads with "self" molecules
    • Binds with CD8 cells
  6. Where do MHC2 cells load?
    • They load out side the golgi in a vesical.
    • Loads with "non-self" molecules
    • Binds with CD4 cells
  7. T cell development
    • Develop in the Thymus - TCR are generated randomly in those T cells
    • TCR must bind MHC 1 or MHC 2 for the T cell to survive - Cells that do not bind are signaled to undergo apoptosis
    • Because Tcells are selected for their ability to bind self MHC, foreign MHC (transplants) trigger T cell rejection
    • Immature T cells binding too tightly to self peptide on self MHC are also killed.
  8. T cell immunity
    *test questions*
    • Tc (cytotoxic (killer) T cells = CD8 recognize and kill virus-infected host cells
    • Th1 cells = CD4 signal infected macrophages to kill pathogens in their pagosomes
    • Th2 cells = CD4 signal B cells to divide and make antibodies
  9. Cytotoxic T cell (Tc, CTL)
    • Tc go to the infection site and find and kill virus-infected cells
    • They kill by releasing perforin makes pores in target cell) and granzymes (cause apoptosis)
    • Tc also kill tumor cells
  10. TB testing
    • Skin testing for TH1 function or delayed type hypersensitivity
    • as small amount of antigen is injected under the skin and a reaction os recorded
    • if you have a positive reaction it means your body has been infected by TB and now have antibodies for it.
  11. B cell activation
    Antigen signal and Th2 signal
  12. Vaccination
    Stimulate with harmless but similar antigen to generate memory cells and antibody
  13. Types of vaccine used in US
    • Whole cell
    • Live attenuated (weakened) virus
    • Killed virus
    • Subunit / Toxoid
    • Recombinant

    All will generate active immunity
  14. Whole cell vaccines
    • Killed cell or inactivated virus is heated
    • Dead, but still has antigenicity
    • is injected and iummunity starts but pathogen can not multiply
  15. Live attenuated virus
    • Can replicate in host
    • Induces Tc Cells and antibodies
    • Unsafe for immunosuppressed people
    • Example: MMR
  16. Inactivated virus or bacterium
    • Cannot replicate in host
    • Safe, induces neutralizing antibodies
    • Example: Rabies, Influenza
    • "killed" vaccine
  17. Subunit vaccines
    • Parts of pathogen - careful as to what subunits used
    • Safe, generate antibodies
    • Example: Pertussis (acellular) Pneumococcal pneumonia (capsule)
  18. Toxoid vaccines
    • Inactivated toxin molecules
    • Safe, generate neutralizing antibodies
    • Example: diphtheria, tetanus
  19. Recombinant vaccine
    • The use of a plasmid attached to a vector
    • Example: Hepatits B virus
  20. DNA vaccine
    • Still under development
    • injecting a plasmid directly into and changing our own DNA to be resistant
    • Currently used for horses
  21. Allergies and autoimmunity
    • Allergies are IgE (antibody) immune response to harmless antigens
    • The immune response causes the disease - Hypersensitivity
    • Other hypersenstivities are caused by IgG or by Th1 or Tc activities
    • Autoimmune reactions occur against self antigens
  22. Hypersensitivities Type 1: Allergy
    • Immediate hypersensitivity
    • Reaction in 30min
    • Inflammation
    • Symptoms depend on where allergen enters and how severe the immune response is
  23. Types of common allergens
    • Pollens
    • Pet dander
    • Dust mite feces
    • Food antigens
  24. Hypersensitivities Type 2:
    • IgG/IgM antibodies bind RBC antigens
    • Complement is activated, lyses RBC
    • ADCC: macrophages or NK cells bind antibody-coated RBC and kill them
  25. Types of type 2 hypersensitiities
    • Rh - mother having a Rh + fetus the body will attack the fetus
    • Medication allergies
    • Mismatched blood (transfusion reaction)
    • Rheumatic fever- occurs after infection (Strep Throat)
    • Autoimmune hemolytic anemia - Body attacks own RBCs

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