Germinal Centers and B Cell Proliferation

Formation of Germinal Centers

• Germinal centers form within B cell follicles in lymphoid organs.
• Initiation:
  • Dendritic cells displaying antigen activate antigen-specific CD4 T cells.
  • Activated CD4 T cells proliferate and mature into effector cells.
  • Effector CD4 T cells activate antigen-specific B cells.

B Cell Activation

• Activation by CD4 T cells leads to B cell proliferation.
• Formation of a primary focus of antigen-specific B cells.

Migration and Proliferation

• B cells from the primary focus migrate to nearby follicles for further proliferation.
• Some B cells remain in the T-cell area temporarily, secreting antibodies before dying.
• B cells in the follicles proliferate rapidly.

Somatic Hypermutation

• B cells undergo somatic hypermutation to introduce variation in their B cell receptors.

Selection Process

• Post-mutation, B cells are tested for their ability to bind antigen.
• B cells that fail to bind antigen or compete effectively with other B cell receptors die.