B-lineage commitment prior to surface expression of B220 and CD19 on hematopoietic progenitor cells.
Mansson R., Zandi S., Anderson K., Martensson IL., Jacobsen SE., Bryder D., Sigvardsson M.
Commitment of hematopoietic progenitor cells to B-lymphoid cell fate has been suggested to coincide with the development of PAX5-expressing B220(+)CD19(+) pro-B cells. We have used a transgenic reporter mouse, expressing human CD25 under the control of the B-lineage-restricted Igll1 (lambda5) promoter to investigate the lineage potential of early progenitor cells in the bone marrow. This strategy allowed us to identify a reporter expressing LIN(-)B220(-)CD19(-)CD127(+)FLT3(+)SCA1(low)KIT(low) population that displays a lack of myeloid and a 90% reduction in in vitro T-cell potential compared with its reporter-negative counterpart. Gene expression analysis demonstrated that these lineage-restricted cells express B-lineage-associated genes to levels comparable with that observed in pro-B cells. These data suggest that B-lineage commitment can occur before the expression of B220 and CD19.