Figure 1.

Biological interactions in the GC relevant to B cell differentiation. Centroblasts (CBs) can be seen on the left in the dark zone, where they rapidly divide and mutate their immunoglobulin V region. After a few hours, CBs migrate to the light zone and become centrocytes (CCs). High-affinity CCs can acquire large amounts of antigen from follicular dendritic cells (FDCs), which makes them more likely to receive survival signals from helper T cells. Low affinity CCs, which acquire little or no antigen, cannot compete for T cell help and die through apoptosis. CCs that have received survival signals may either recirculate into the dark zone for another round of division and hypermutation, or leave the GC and differentiate into PCs or MBCs.