B cells

这是一篇关于B cells的思维导图，主要内容有development(maturation)、Training、roles、Some terms。

B cells

• development(maturation)
  • Stages
    • Pre-B cells
      • progenitor B cells
      • Early Pro-B cells
      • Late Pro-B cells
      • large pre-B cells
      • small pre-B cells
    • Imature B cells
    • Mature B cells
    • Activated B cells(effector B lymphocytes)
      • Memery B cells
      • plasma B cells
        • location
          • mosly in tissues, some are in circulations
    • Naive lymphocytes
      • B cells have not been activated
  • VDJ recombination in heavy-chain V region
  • VJ recombination in light-chain V region
  • after the BCRs on Mature B cells encounter antigens, it will undergo colonal expansion, also memory B cells are generated.
    • The second immune response is more powerful and more efficient
  • Surface changes during development
    • proteins remain unchanged during maturation
      • TACI
      • BCMA
      • BAFF-R
        • B cell-activating factor receptors
        • The Belimumab is moloclonal antibody against the soluable form of BAFF-R
        • blisibimod can inhibits both soluable and membrane form of BAFF-R
    • proteins changes during B cell maturation
      • CD20
        • not on pre-pro cells
        • not on plasma cells
        • present on all the other staged cells
      • pre-B cell only
        • CD19
        • CD127
      • Other detailed changes
        • • This developmental steps is regorously followed, if any steps failed, the cell will undergo appoptosis.(clonal deletion)
• Training
  • location
    • bone marrow: central lymphoid organ
  • goals
    • test for auto-reactivity
    • Immature B cells bond too tightly to self antigens will undergo apoptosis
  • 3 underlying mechanisms
    • Clonal deletion
      • the removal, usually by apoptosis, of B cells of a particular self antigen specificity.
    • Receptor editing
      • Self reactive B cells have one chance to rearange their BCR, but just one chance
      • Recombination Activating gene (RAG) are first continouly expressed
      • Then the BCR lightchain gene will rearange once with the helping of RAG
    • Anergy
      • B cells first bind with small, soluable weakly cross-linking self antigens
      • B cells will enter a state of permanent unresponsiveness
• roles
  • Immune survaliance
    • locations
      • blood and lymphatic system
    • millions of mature B cells all with different BCRs, they will become activated BCR encounters its cognate antigen, and recieves the signal from T helper cells
      • 10^9 possible specificities
    • It will follow the clonal expansion, the two types of cells are differentiated
      • something more
        • It might with or without an intermediate step during the differentiation
        • A group of B cells are supermaturated, this type of B cells may shift between plasma B cells and Memory B cells.
      • plasma B cells
        • most
        • secretion of antibodies with the same epitope binding specificity of the BCR getting activated at the first step.
      • Memory B cells
        • The small group of cell that will survives very long
        • Can be reactivated only by the same epitope
          • Each reactivation cycle will produce higher proportion of Memory B cell, therefore they can elicit stronger immunities for the next time.
            • what doesn't kill me make me stronger
          • affinity maturation
            • The B cells binding with epitopes with higher affinity will have high affinity rate.
  • production of antibodies
  • antigen-presenting cells (APCs)
  • development of memory B cells
  • release of cytokines
• Some terms
  • BCR
    • a membrane bonded Immunoglobin
    • Only presents on B lymphocytes
• Pathogens just give up?
  • Never: they evolve faster
    • They damage host faster
      • Subtopic
    • They prevent host immune synstem
      • against phagocytosis
        • capsules
      • against T cells
        • superantigens
      • against antibodies
        • Antigenic variations
          • alter surface antigen
  • virulence factors
    • adhesin
    • impedin
    • toxin
      • exotoxin
        • Diphtheria toxin
        • Botulinum toxin
        • Tetanus toxin
      • endotoxin
        • Subtopic
    • encoding
      • plasmid, phage, genomic (pathogenicity) islands