What are the six stages of B cell development?
1. Repertoire assembly: generation of diverse clonal B cell receptors in bone marrow
2. Negative selection: alteration, elimination, or inactivation of B cell receptors that may be self reactive
3. Positive selection: promotion of fraction of immature B cells to become mature; occurs in secondary lymph nodes (spleen, lymph nodes, mucosa of lymphoid tissue)
4. Searching for infection: recirculation of mature B cells between lymph, blood,a nd secondary lymphoid tissue
5. Finding infection: activation and clonal expansion; pathogen derived antigens in secondary lymphoid tissue
6. Attacking infection: differentiation to antibody-secreting plasma cells and memory B cells in secondary lymphoid tissue