Mature B Cells Development of IgM+IgD+mature B cells Predominantly in bone marrow Can also occur in secondary lymphoid organs ■Activation Response to foreign Ag Occurs primarily in secondary lymphoid organs(lymph node and spleen)in the germinal centers Enlarge to become B cell "blasts" Proliferate and differentiate Plasma cells>class switching Memory B cells>class switch but non-proliferating,long-lived Mature B Cells ◼ Development of IgM+IgD+ mature B cells ◼ Predominantly in bone marrow ◼ Can also occur in secondary lymphoid organs ◼ Activation ◼ Response to foreign Ag ◼ Occurs primarily in secondary lymphoid organs (lymph node and spleen) in the germinal centers ◼ Enlarge to become B cell “blasts” ◼ Proliferate and differentiate ◼ Plasma cells → class switching ◼ Memory B cells → class switch but non-proliferating, long-lived