18- B cell Development

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Created by
Ashley

Cards (17)

  • B Cell
    • Arise in bone marrow then finish development in spleen
    • Only cell that produces immunoglobulins
    • Activates by binding antigen and signal transduction
  • Life cycle of B cell
    1. Early Pro-B
    2. Late Pro-B
    3. Pre-B
    4. Immature B
  • Early Pro-B
    • DJ heavy chain recombination
    • Start of V-DJ H chain recombination
  • Late Pro-B
    1. DJ heavy chain
  • Pre-B
    • Heavy chain expressed as pre-BCR
    • Lots of cell division- goes from large pre to small pre
    • VJ light chain recombination
    • Make sure that the heavy chain works with pre-B light chain
  • Immature B
    • IgM surface receptor expression
    • Negative selection (Deletion if bound to light, receptor edition)
  • Cytokines involved
    IL-7, CD19
  • B Cell Development in Bone Marrow
    1. HSC circulates in blood then makes contact with CXCL12 to become pre-pro B cells
    2. Then contact IL-7: when Pro-B cells then progress through Pre-B to immature B stages
  • Immature B Cells

    • Proper IgM on cell surface with Iga and IgB
    • Exposed to self antigens: if it bonds, negative selection (apoptosis)
  • Becoming Mature B cells
    1. 2 transitional stages (T1: low IgD expression, T2: intermediate IgD expression)
    2. Then go through positive and negative selection
    3. BAFF makes sure IgD can pass a viable signal
  • Mature B cells
    • Fully functional and ready to circulate
    • If in periphery and react to self: Apoptosis or Anergy (inavation)
  • B Cells to peripheral Sites
    Lymph node chemokines bring dendritic cells and B cells in and out with gradients
  • Process of B-cell Second Signal
    1. T dependent: Need a helper T cell in the lymph node (CD40/CD40L)
    2. T Independents: not cell involved (Engage B cell receptor and PRRs, Engage B cell receptor and CD21 (complement) with C3d)
  • Somatic hyper mutation/affinity maturation improves antigen binding dramatically
  • Apoptosis Intrinsic Pathway

    Stress, radiation, remove growth factors
    Signalling through TCR with no second signal
    Strong TCR signals during development
  • Apoptosis Extrinsic Pathway

    Caused by membrane receptors engaging extracellular ligands
  • Apoptosis

    Activates caspases