Proper development and differentiation of B lymphocytes is es- sential to ensure that an organism has the ability to mount an effective humoral immune response against foreign antigens. The immune system must maintain a balance between the deletion of harmful self-reactive B cells and the generation of a diverse rep- ertoire of B cells that has the ability to recognize an almost un- limited array of foreign antigens. The need to delete self-reactive cells is tempered by the need to avoid the generation of large functional holes in the repertoire of foreign antigen-specific B cells that patrol...