Disposed Flashcards
What is the dark zone selection model of GC migration? (to account for selection-linked mutation)
B cell selection occurs within the dark zone
– Higher-affinity B cells are retained and continue proliferating in the dark zone
– Lower-affinity B cells die by apoptosis
Selected B cells directly migrate out of the germinal center
What is the cyclic re-entry model of GC migration? (to account for selection-linked mutation)
B cell alternate between dark and light zones
– B cells migrate to the light zone where their mutated BCRs are tested for antigen affinity.
– Higher-affinity B cells are selected for survival and proliferation
–Selected B cells return to the dark zone to undergo additional rounds of proliferation and mutation
– Lower-affinity B cells fail to compete for antigen and T cell help, undergoing apoptosis