Activation of NF-κB promotes the transition of large, CD43+ pre-B cells to small, CD43- pre-B cells

The regulation of the transcription factor nuclear factor-kappa B (NF-kappa B) during B-cell development was examined using cells isolated from the bone marrow of transgenic mice expressing a kappa B luciferase reporter gene. The results indicate that the highest level of NF-kappa B activity is present in cells expressing the pre-B-cell receptor. Furthermore, cross-linking of Ig beta on CD43(+) pre-B cells is able to activate NF-kappa B in recombination-activating gene 1-deficient mice, preceding their further differentiation into CD43(-) pre-B cells. Expression of a dominant negative form of I kappa B alpha using a transgenic approach or by retroviral infection leads to a reduction in the number of CD43(+) pre-B cells. These data therefore indicate that activation of NF-kappa B in CD43(+) pre-B cells, as a result of signaling by the pre-B-cell receptor, facilitates the continued development of large, CD43(+) pre-B cells into small CD43(-) pre-B cells.