T cells S3M1

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lancesadams
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100109
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T cells S3M1
Updated:
2011-09-10 17:26:58
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Ross S3M1
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Immunology
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  1. T cell receptors are always found where
    Membrane bound
  2. What are the two major differences between BCR's and TCR's
    • BCR's can be specific for proteins, lipids, carbohydrates, and phospholipids and recognize them without MHC
    • TCR's recognize only peptides and must use MHC
  3. Where do T cells mature
    Thymus
  4. Tumor and allograft rejection is mediate mainly by
    T cells
  5. What are some of the Thymic peptides
    • Thymosin alpha
    • Thymosin beta
    • Thymulin
    • Thymopoietin
    • Thymic humoral factor
  6. What is the role of Thymic peptides
    They influence the phenotypic maturation of progenitor cells from the bone marrow and modulation of functions of mature T cells
  7. T cell progenitors enter the thymus where
    At the junction between the cortex and medulla
  8. In what direction do the T cells migrate in the thymus as they develop
    • Subcapsular zone
    • Cortex
    • Medulla
  9. T cell receptor gene rearrangements do not occur until
    The cells enter the thymus
  10. When do the T cells begin expressing the CD2 adhesion molecule
    Within one week of being in the Thymus
  11. The alpha chain of the T cell receptor has what gene segments
    V and J
  12. The ß chain of the T cell receptor has what gene segments
    V, D, and J
  13. Thymocytes with ß chain will associate with
    Pre-T alpha chain and the CD3 molecule
  14. In what ways are TCR's tested
    • 1. Ensure the TCR can interact with self MHC (positive selection)
    • 2. Ensure that TCR is not specific for self-MHC or self antigen (negative selection)
    • "not too hot or cold, but just right"
  15. In order for T cell destruction as a result of too strong of binding to a self antigen, the self antigen must be present where
    In the thymus
  16. Which are longer lived, B cells or T cells, and for potentially how long
    • T cells
    • Years
  17. What are the two forms of TCR's
    • alpha beta (common)
    • gamma delta (uncommon)
  18. What TCR operate without MHC
    gamma delta
  19. What is a Treg
    • regulatory T cell
    • Tregs suppress the response of self reactive CD4 T cells
  20. A progenitor T cell that becomes committed to T cell linage expresses what
    CD2
  21. Rearrangement of TCR involves what genes
    RAG and TdT
  22. Rearrangement of TCR only happens
    During development
  23. Expression of how many TCR can happen at one time
    One
  24. Tregs are characterized by their expression of
    CD25 and use of FoxP3
  25. A deficiency of FoxP3 would have what effect
    • Fatal autoimmune disorder
    • Found mostly in males due to its being encoded in the X chromosome
  26. What is the function of CD3, and what cells is it found on
    • Helps transduce signal when antigen-MHC complex binds TCR
    • Found on all T cells
  27. What is the role of CD4 on T cells
    • Expressed on Helper T cells
    • Attaches to Class II MHC
    • Promotes adhesion to APC and to B cells
  28. What is the role of CD8
    • Expressed on Cytotoxic T cells
    • Attaches to Class I MHC
    • Promotes adhesion to affected cell
  29. What is the role of CD28, and what cells can it be found on
    • Provides co-stimulatory signal to T cells
    • Found on many Helper and Cytotoxic T cells
  30. What does CD28 bind to
    CD80/86 (B7)
  31. What is the role of LFA-1, and what cells express it
    Promotes cell to cell adhesion and is found on most WBC's including T cells
  32. What is the ligand on the target cell that LFA-1 binds to
    ICAM-1
  33. What beyond binding of the ligand and MHC must happen for the T-cell to activate
    There must also be a co-stimulatory signal involving CD80/86 on the APC and CD28 in the T-cell to connect triggering activation
  34. What triggers the expression of CD80 on the APC
    • TLR's or other receptors of innate immunity
    • They are only expressed on the APC during infection
  35. What happens to a naive T cell when it attaches to a APC that does not express B7 (CD80/86) along with the MHC+ligand
    The cell becomes non-responsive to the antigen and cannot become subsequently activated
  36. When are CD80/86 (B7) no longer necessary
    After the T cell becomes activated it no longer needs the co-stimulatory signal
  37. Activated T cells under go clonal expansion and differentiation driven by what
    Cytokine IL-2 (autocrine secretion from the T cell)
  38. When do the T cells acquire the proteins needed for their effector functions
    Following IL-2 release, during differentiation
  39. What do CD4 T cells change into from Th0, and what initiates it
    • Th1, Th2, or Th17
    • Initiated by cytokines released by APC's and NK's
  40. During T cell differentiation, what cytokine exposure makes makes a Th1
    IL-12 and IFN-gamma
  41. During T cell differentiation, what cytokine exposure makes a Th2
    • IL-4
    • IL-5
  42. During T cell differentiation, what cytokine exposure makes a Treg, and what does it secrete
    • TGF-ß
    • Secrete TGF-ß and IL-10
  43. During T cell differentiation, what cytokine exposure makes makes a Th17
    • TGF-ß
    • IL-6
    • IL-1ß
  44. What are the effector molecules secreted by CD8 T cells
    • Perforin
    • Granzymes (activate apoptosis)
    • Granulysin (antimicrobial action + induce apoptosis)
    • Fas ligand
  45. Th1 cells secrete
    IL-2 and IFN-gamma
  46. Helper T 1 cells target
    Extracellular bacteria
  47. T helper 2 cells target
    Helminth parasites
  48. T helper 17 cells target
    Extracellular bacteria
  49. Th2 cells secrete
    • IL-4
    • IL-5
    • IL-10
    • IL-13
  50. How does the expression of FasL and CD40L compare in Th1 and Th2 respectively
    • Th1 expresses more FasL
    • Th2 expresses more CD40L
  51. Th1 responses often lead to what type of killing
    Macrophage activation for pathogen killing
  52. Th2 responses largely influence what differentiation
    B cell differentiation resulting in a large antibody production (especially IgE for Helminths)
  53. What does the Th17 play an important role in
    • Adaptive immune responses to extracellular bacteria and fungi
    • It is characterized by the release on IL-17
  54. IL-17 initiates what
    Inflammatory response by neutrophils
  55. What effect does CD8 have on cells containing infection
    It causes them to undergo apoptosis
  56. What is the HIV receptor
    CD4+ expressed on T cells
  57. What is the ratio of CD4 and CD8 expression
    CD4 is 2x as prevalent
  58. What cell surface receptors are found on Treg cells
    CD4 and CD25

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