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. Author manuscript; available in PMC: 2013 Jan 27.
Published in final edited form as: Immunity. 2012 Jan 27;36(1):13–21. doi: 10.1016/j.immuni.2011.11.017

Figure 1.

Figure 1

B-1 and B-2 development. B-2 cells (Top) are produced in the bone marrow after birth. Common lymphoid progenitors (CLP) mature sequentially through pre-pro-B, pro-B, and pre-B (not shown) cell intermediates into immature sIgM+ B cells (shown as “B cell” in figure). Pre-pro-B cells are referred to as B-2 progenitors in the text. Immature sIgM+ cells migrate to the spleen where they mature through B-2 transitional 1 (T1) and Transitional 2 and 3 (T2 and T3) stages into Follicular (FO) or Marginal Zone (MZ) B cells. The stages of B-1 development are increasingly well defined, and it is now possible to propose a model of development based on the data summarized in this review (Bottom). Mature B-1 cells are generated from B-1 specified CLPs that sequentially differentiate through B-1 progenitor, pro-B, pre-B (not shown) and immature sIgM+ B-1 cell stages. The latter cells then mature in the spleen through the Transitional cell stages shown. Mature B-1 cells that migrate to serous cavities acquire the B-1a and B-1b phenotype. The figure also shows that B-1, but not B-2, progenitors are TSLP responsive, that B-2, but not B-1, development is dependent on IL-7, and that B-1 transitional cell survival and maturation is BAFF and NF-κB2 independent.