In vitro and in vivo plasticity of Pax5-deficient pre-B I cells.

In mice deficient for the transcription factor Pax-5, B cell development is blocked at the pre-B I cell stage. Like wild type, Pax-5-/- pre-B I cells can be grown long-term in vitro in the presence of stromal cells and IL-7. However, unlike their wild type in vitro grown counterparts, Pax-5-/- pre-B I cells posses an extraordinary developmental plasticity showing hematopoeitic stem cell features such as multipotency and self renewing capacity. Here we review and discuss this in vitro and in vivo plasticity of Pax-5-/- pre-B I cells.