Schematic representation of normal B-cell ontogeny in the germinal center.

Naïve B-cells encounter antigen and undergo proliferation, clonal expansion, somatic hypermutation and class-switch recombination in the germinal center microenvironment. The resulting B-cell clones with high affinity antibodies are positively selected to differentiate into plasma cells and secrete large quantities of specific antibodies or become memory B-cells that recognize and respond to repeat antigen exposure. The remaining B-cell clones are eliminated by apoptosis.