Chapter 6 Flashcards
(13 cards)
Process of phase 1
Stem cell/lymphoid progenitor cell (binding)> Early pro-B cell (activation of kit= proliferation of B cell)> Late pro-B cell (IL-7 stimulates growth & proliferation)> Pre-B cell (recombination of VDJ and VJ genes)> Immature B cell
Early stages (phase 1) are dependent on ________
bone marrow stromal cells
In phase 2, tolerance to what is developed?
Self-polysaccharides, self-lipids, self-nucleic acids, self-proteins
What does Tolerance mean?
the failure to respond to an Ag; normal response to self-antigens, B cell survives
What happens during phase 2
> Selection and further development of the B-cell repertoire in bone marrow
Self-reacting immature B cells are eliminated by contact with self-antigens
Clonal deletion of B cells (NEGATIVE selection)
Process of immature B cells in bone marrow
-No reaction with self antigen> Immature B cell moves to the blood and expresses IgD and IgM
-Reaction with a self antigen (common cell-surface antigens)> Immature B cell is retained in bone marrow (alteration or clonal deletion)
Receptor editing can rescue a self-reactive B-cell by:
> Replacement of light chain
Changes in Ag specificity
Phase 3 process
Immature B cells finish maturation in lymph node follicles (or other secondary lymphoid tissues)> cytokines from dendritic cells> mature B cells (more IgD)
What is phase 5?
Antigen recognition
>Mature B cells encounter Ag in lymph node
> Activated by CD4 T cells (proliferation)
> Some B cells move to medulla (IgM secreting plasma cells)
> Some B cells migrate to primary follicle (form germinal centers (proliferation & class switching, hypermutations, affinity maturation)
What is phase 6?
Differentiate into memory B cells and IgG secreting plasma cells
Medullary plasma cell secretes:
IgM
Plasma cell secretes:
IgG/IgA/IgE
