humoral immunity

Card Set Information

humoral immunity
2011-08-24 09:33:04
immunology humoral immunity

MS1/Mod 1: immunology; humoral immunity
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  1. early Pro-B cell
    rearrangement of D-J heavy chain genes
  2. late Pro-B cell
    rearrangement of VD-J heavy chain genes
  3. large Pre-B cell
    • VDJ heavy genes rearranged
    • mu chain at surface of B cell w/ surrogate L chain
  4. small Pre-B cell
    rearrangement of V-J light chain genes
  5. immature B cell
    heavy and light chains come together on surface, quindi IgM now expressed on cell surface
  6. mature B cell
    IgD and IgM made from alternatively spliced H chain transcripts and are expressed on surface
  7. What is the significance of mu heavy chain expression on cell surface?
    signals cessation of heavy chain gene rearrangement and beginning of light chain gene rearrangement
  8. What is a surrogate L chain?
    made of VpreB and lambda 5 proteins assemble together to act as "L chain" on surface of large Pre-B cell with mu heavy chain

    signals to stop mu chain rearrangement and begin L chain rearrangement
  9. What happens when the small Pre-B cell becomes an immature B cell?
    light chain gene rearrangement has been successful; now a full receptor expressed on outside; surrogate L chain no longer needed (VpreB and lambda 5 inhibited by completed real L chain)
  10. How does RAG play a role in gene rearrangement?
    stops expression of genes by phosphorylation in large Pre-B cell stage to stop rearranging but turns rearrangement back on for L chain rearrangement
  11. How are immature B cells and negative selection related?
    immature B cells are sensitive to negative selection in the bone marrow
  12. What is negative selection?