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Flashcards

Block 1 Immunology - Part 2

Eva Davenport Phase 2 Block 1 English 45 cards

Cards in this deck (45)

  1. 1Cq1 ComplimentWhen antibodies bind to foreign cells, allows for binding of the complement Cq1, initiating a compliment cascade - opsonzie the antigen, kill bacteria or inactivate virus. Important in IgM antibodies since they are not very reactive with phagocytes for direct opsonization
  2. 2Antigenic NeutralizationAntibodies bind to toxins, preventing it from interacting with host receptor. Can also bind to antigens on the surface of viruses. Generally mediated by IgG antibodies because of their high affinity
  3. 3Intracellular vs. Extracellular PathogensAntibodies/antigen interactions happen extracellularly because antibodies are too big to enter cells. For intracellular pathogens, need to inititate antibody-dependent cell-mediated cytotoxicity via Natrual Killer cells (link between humoral and cell-mediated immunity)
  4. 4Delayed Type Hypersensitivity ReactionExperiment to illustrate priming of the imuune system: inject a mouse with antigen, wait two weeks, then see a secondary immune response when primed mouse was given a small amount of the same antigen at a distal site/different location
  5. 5Two Defining Characteristics of the Adaptive Immune ResponseSpecifity (specific antigens elicit specific responses) and Memory
  6. 6T cell receptor vs. B cell receptor StructureT cell: alpha and beta chains, some gamma and delta chains
    B cell: Heavy and Light chains
    Both clonotypic heterodimers
  7. 7T cell receptor vs. B cell receptor Binding SidesT cell: monovalent, 1 antigen binding site, liek Fab of IgG
    B cell: divalent to decavalent
  8. 8T cell Receptor vs. B cell receptor Effector MechanismsT cell: doesn’t bind soluble native antivens - has MHC-antigen recognition of antigen. Cell surface receptors only, not secreted. No somatic hypermutation, no isotype switching
    B cell: secreted as Ig, somatic hypermutation and isotype switching
  9. 9T cell receptor vs. B cell receptor Associated complexesT cell: non-polymorphic CDs signaling complex (delta, gamma, epsilon, mu)
    B cell: non-polymorphic alpha and beta signaling proteins
  10. 10B cell vs. T cell in antigen recognition - major difference!B cell receptor and immunoglobin are able to bine antigens in their isolated and unprocessed state. T cell receptors only interact with antigens when it is processed into short, linear peptides and presented by specific molecules expressed on the surface of antigen-presenting cells (MHC molecules)
  11. 11Thymic SelectionEach T cell receptor is matched with a particular MHC molecule/antigenic peptide combination during this process, producing a T cell repertoire that is unique for each individual beacuse of their different MHC molecules
  12. 12ThymocytesT cell precursers. Originate in the bone marrow and migrate to the thymus to mature
  13. 13Positive Thymic SelectionThymocytes enter thymus, clonotypic T cell receptor genes rearrange. Once alpha chains are produced, mature TCRs are expressed on cell surface. Cell is actually programmed to die, however, if the new TCR interacts with an MHC molecule present in the thymus, the thymocytes are rescued!
  14. 14CD3 signal transduction complexWhat causes thymocytes to expressed TCR early in the selection processes in order to bind with an MHC molecule and avoid cell death
  15. 15Double Positive ThymocytesProducts of the first step of thymic selection (positive selection). Cells express both CD4 and CD8
  16. 16Negative Thymic SelectionDouble positive thymocytes come into contact with dendritic cells (at the cortico-medullary junction). If the TCR reacts strongly to the MHC molecule on the dendritic cell, it is deleted. If interaction is appropriate, it survives and loses one of its CD4/8 molecules depending on the MHC molecule type (single positive)
  17. 17CD moleculesSystemic nomenclautre for molecules expressed on the surface of cells, especially leukocytes - give external characteristics to a cell
  18. 18T cell (helper/Cytotoxic) B cell NK cell Lineage Status Designation by CD markersHelper T cell: CD3 and CD4
    Cytotoxic T cell: CD3 and CD8
    (T cell: CD3)
    NK Cell: CD3 and CD15
    B Cell: CD19
  19. 19Clonal Selection TheoryFoundation of adaptive immunity
    1) generation of diversity through somatic gene rearrangement
    2) Alleleic exclusion to restrict clones to a single specificity
    3) Linking antigen recognition to cellular activation
    3) Tolerant to self
  20. 20CD62LAllows for circulating naive T cells to enter lymph nodes for initial encouter with antigen that their receptor is specific for - priming. T cell then look for dendritic APCs with antigens that it can recognize (then it leaves lymph node to site of infection)
  21. 21T Cell 1) antigen-specific recognition complexes 2) Co-receptors 3) Accessory molecules 4) Adhesion molecules1) TCR - MHC/peptide
    2) CD4 - MHC II, CD8 - MHC I
    3) CD28 - B7
    4) ICAM - LFA-1
    (Work to enhance the T Cell/APC interaction - requres sustained close contact)
  22. 22T cell activation with receptor aggregation OverviewAPC/T cell —> co-receptor complexes accumulate —> Kinase molecules recognize CD3 —> local phosphorylation —> Increased intracellular Ca —> activation of transcription factors —> new proteins that affect behaviour of activated T cell —> have cytokine mediated proliferation!
  23. 23T cell activation: Early steps (0-30 minutes)Receptor/co-receptor engagement
    Accessory engagement (B7-CD28)
    Adhesion molecule engagement (ICAM/LFA-1)
    Have phosphorylation, Ca influx, activation of TFs, translocation to nucleus and trascription of genes
  24. 24T cell activation: Intermediate steps (30 minutes - 48 hoursTranslocatiopn, cytokine production, receptor expression and DNA replication
  25. 25T cell activation: Late steps (>48 hours)Cell division, differentiation, acquisition or effector function
  26. 262 classes of Helper T cells (CD4)TH1: release cytokines to activate and recruite other leukocytes to site of infection (cell mediated immunity)
    TH2: release cytokines and express CD40 ligand to drive proliferation and differentiation of antigen activated B cells (humoral immunity)
  27. 27Cytotoxic T cell FunctionCD8 cell proliferates and aquires perforin and granzymes (toxic molecules) —> clonol proliferation. Upon second interaction, T cell makes microtubule tracks to release toxins. Perforin makes holes in the presence of Ca. Granzyme enters pores and triggers apoptosis.
  28. 28TH1Induced by: IL-12
    Cytokines= IFN-gamma, IL-2
    Cell-mediated immunity
  29. 29TH2Induced by: IL-4
    Cytokines = IL-3, IL-4, IL-5
    Responds to allergins and worms
  30. 30TH17Induced by: TGF-beta and IL-21
    Cytokiens = IL-17, IL-22
    Proinflammatory response to fungi and bacteria
  31. 31THregInduced by: TGF-beta
    Cytokines = TGF-beta, IL-10
    Inhibits functions of other sets of T cells
  32. 32Contact dependent/independent effector in functionsIn T cell
    Dependent = cytotoxicity/CD40L
    Independent = cytokine production
  33. 33Affinity MaturationB cells leave bone marrow
    1) by themselves, mature to IgM via antigenic stimulation
    2) Interaction with T cells = real time evolution. B cells undergo isotype switching and affinity maturation
  34. 34Steps of T cell activation via B cellsBest epitopes that activate B and T are physically linked but not overlapping.
    B cell consumes entire protein —> MHC II molecules brought to surface, bind to CD4 T cell —>B cell express T cell-costimulatoruy molecules —> Tcell activated by B-cell by CD40L expression and cytokine releasse
  35. 35CD40/CD40LInteraction between B cell and T cell, helps boost signalling
    Helper T cells expresses CD40L - rescues B cells from apoptosis in the Light Zone
  36. 36B7B cell expresses B7 and MHC class II molecules when initially activated
  37. 37FollicleB cells organize themselves into structures called follicles within the lymph node, before an antigen is instroduced to the system
  38. 38Follicular Dendritic NetworkStructure surrounding the B cell follicle that contains dendritic cells and some T cells
  39. 39Follicular Mantle ZoneWhere a high density of naive B cells are surrounding the germinal centre
  40. 40Germinal CentreSite of T cell dependent B cell differentiation
  41. 41Dark ZoneThe area of most intense B cell proliferation, where somatic hypermutation takes place
  42. 42Light ZoneB cells moving through the light zone are programmed to die unless rescued by interacting T cells, specific for the antigen driving the immune response. The CD40L T cell signal rescues the B cells and directs isotype switching depending on what cytokines it released - B cells compete to be rescued
  43. 43Which Ig isotype can cross the placenta?IgG1 and IgG3
  44. 44Which Ig isotype initiates allergic reactionsIgE
  45. 45Which Ig isotype neutralizes pathogens in the mucusIgA (and IgG)

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Phase 2 Block 1 Flashcards on Block 1 Immunology - Part 2, created by Eva Davenport on 25/01/2018.
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Eva Davenport
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