germinal centers where B cells proliferate and undergo both isotype switching and somatic hypermutation form within the B cell follicles in lymphoid organs the formation of germinal centers starts when dendritic cells displaying antigen on their surface activate antigen specific cd4t cells which proliferate and mature into affector cells capable of activating antigen specific B cells once activated by a cd4t cell the B cell PR erates to form a primary focus of antigen specific B cells B cells from the primary focus migrate to nearby follicles and proliferate other B cells from the primary focus persist in the t- cell area for a short while secreting antibody but eventually die the B cells that enter the follicle begin to proliferate rapidly during this time they also undergo sematic mutation to introduce new variation into the B cell receptor B cells undergo a process of selection after sematic mutation when The receptors are tested for their ability to bind antigen those that fail to bind or that fail to compete efficiently against other B cell receptors die