immuno chapter 8.txt

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immuno chapter 8.txt
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2011-03-03 16:04:42
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Immuno chapter 8
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  1. ��What cells are the main activators of T cells?
    Dendritic cells
  2. Where are T cells activated?
    draining lymph node, bronchial-associated mucosal tissue, peyer's patches and GALT, spleen
  3. How are antigens captured by dendritic cells?
    TLR medieated endocytosis, macropinocytosis, cross-presentation
  4. Macropinocytosis
    non-specific uptake of a large amount of fluid
  5. Cross-Presentation
    capture of antigen from an infected cell by a professional APC and delivery to the MHC I pathway
  6. What happens after a DC uptakes an antigen?
    increases efficiency of antigen capture, receptor expression that responds to chemokines, maturation of DC so they can present to T cells
  7. What forms of DC are in the peripheral tissue?
    Immature DC- MHC is in endocytic vesicles, antigen capture occurs
  8. What happens when the DC is in circulation?
    MHC starts to separate
  9. What happens to the DC in lymphoid tissue?
    it becomes mature with its MHC on the surface
  10. How do naive t cells enter the lymph node?
    HEV by homing process
  11. What happens to Naive cells that bind to antigen?
    they are detained and slowly proliferate
  12. How does homing of naive T cells occur?
    chemokines are secreted by stomal and DCs in the lymphnode. The T cell has a receptor that will bind to the chemokines on HEV surface.
  13. L-selectin on the ____ binds to _____ on the ______ resulting in _____
    T-cell; glycam-1; HEV; loose binding
  14. T-cell binds chemokine resulting in ____
    activation of LFA-1
  15. LFA-1 on the ____ binds _____ on the _____ resulting in ______
    T cell; icam 1; HEV; tight binding
  16. What is the function of transient binding?
    the T cell can scan for MHC-peptide complexes.
  17. What is co-stimulation?
    Professional APC gives 2 signals to activate the naice T cell.
  18. What two bindings lead to co-stimulation?
    TCR binding to peptide-MHC and CD28 on Tcell binding to B& on professional APC
  19. What happens when the t cell becomes activated?
    it starts to express CTLA4 and binds to B7 more tightly resulting in reduced proliferation
  20. Where are dendritic cells located in the lymph node?
    only in the cortical (t cell) area
  21. Activated DC
    make B7, more MHC, chemokine, and DC-SIGN to attract and bind T cels
  22. Where are macrophages located in the lymph node?
    cortex and follicles
  23. What is the role of macrophages in the lymph node?
    clean up antigens/pathogens that arrive to the lymph node, process and prevent antigens, remove unwanted lymphocytes, express B7 and MHC once activated
  24. Where are B cells located in the lymph node?
    lymphoid follicles
  25. what is the role of B cells in the lymph node?
    antigen capture by receptor mediated endocytosis and presentation so B cell is usualy presenting peptides from antigen bound by the BCR
  26. Do B cells participate in naive T cell activation?
    no
  27. What role does tyrosine kinase have in activation of t cells?
    cell proliferation and development of effector functions; IL-2 is produced
  28. What is the process of T cell activation?
    TCR binds to MHC class II. this binding triggers phosphorylation of ITAMs. Binding of CD4 to MHC II leads to ZAP-70 binding to the phosphrylated zeta chain.
  29. IL-2
    leads to t cell differation by binding first with low affinity and then high affiniity inducing t cell proliferation
  30. What happens if CD28-B7 does not bind
    t cell becomes anergic
  31. IL-12 and IFN-gamma lead to more (TH1 or TH2)
    TH1
  32. IL-4 leads to more (TH1 or TH2)
    TH2
  33. TGF-beta leads to more
    Treg
  34. TH1
    secretes IL-2 and Ifn-gama leading to macrophage activation
  35. TH2
    secretes IL-4 and IL-5 leading to B cell activation and differentiation
  36. What is the main stimulator of CD8 cell activation?
    dendritic cells
  37. How can CD4 help activate CD8 cells?
    CE4 activates an APC cell which activates CD8 cells
  38. What are effector T cells
    can bind to a wide range of cells that do not express B7
  39. What cells produce cytokines?
    T cells
  40. What cells produce cytotoxins?
    CD8 t cells
  41. What cascade do cytokines initiate?
    receptor dimerization, JAKs and STATs which lead to transcription
  42. Which of the following is/are step(s) where B cell proliferation occurs?
    Immediately after B cell activation AND after the large pre-B cell stage
  43. Is IL-2 autocrine or paracrine?
    auto
  44. Is IFN gama autocrine or paracrine?
    para
  45. Does CD8 bind to CD40 or FAS?
    FAS
  46. Does CD4 bind to CD40 or FAS?
    CD40
  47. How do CTL induce apoptosis?
    they synthesize cytotoxins in inactive form when the T cell is activated in lymph node. They release the lytic granule contents when specifically bound to peptide:MHC I complex. They also secrete IFN gamma to inhibit viral replication and attract macrophages.
  48. How do cytotoxins kill a cell?
    perforin makes holes in mambrane and granzymes initiate apoptosis
  49. How does FAS kill a cell?
    FAS ligand binds to Fas on the target cell
  50. Activation of macrophage at infection site
    • Causes more efficient fusion of phagosomes to lysosomes
    • Release of cytotoxic molecules (free radicals, NO and proteases)
  51. Activation of macrophage at lymph node
    • Amplify immune response
    • Increased expression of MHC II and B7  positive feedback that results in more activation of macrophages at the infection site
  52. What two signals are required for activation by TH1?
    IFN gamma and CD40 binding
  53. How else can macrophages be activated?
    CD8 t cells produce IFN gammma plus presence of LPS
  54. How does TH1 control the response to intracellular macrophage pathogens?
    IFN gammma and CD40 super activates the macrophage to remove the pathogen
  55. How does b cell activation by TH2 occur?
    CD40 ligand is synthesized by the t cell, IL-4 is secreted.
  56. What is the end result of b cell activation
    b cell proliferates and differentiates
  57. Cognate interaction
    two different parts are recognized on the same entity
  58. In a conjugate vaccine, what does the BCR recognize?
    polusaccharide
  59. In a conjugate vaccine, what epitope is displayed by MHC II?
    toxoid
  60. What immunosuppressive cytokines do regulatory T cells produce?
    IL-4, IL-10, and TGF-beta

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