PT  - JOURNAL ARTICLE
AU  - Hunte, B E
AU  - Hudak, S
AU  - Campbell, D
AU  - Xu, Y
AU  - Rennick, D
TI  - flk2/flt3 ligand is a potent cofactor for the growth of primitive B cell progenitors.
DP  - 1996 Jan 15
TA  - The Journal of Immunology
PG  - 489--496
VI  - 156
IP  - 2
4099  - http://www.jimmunol.org/content/156/2/489.short
4100  - http://www.jimmunol.org/content/156/2/489.full
SO  - J. Immunol.1996 Jan 15; 156
AB  - We have investigated the role of flk2/flt3 ligand (FL) in B cell lymphopoiesis. The ability of FL to stimulate the growth of immature B cells was assessed using distinct populations: CD43lowB220+ pre-B cells, CD43+B220+ pro-B cells, and CD43+B220low progenitors. FL failed to affect the growth of the pro-B or pre-B cells whether used alone or in combination with stem cell factor (SCF) or IL-7. In striking contrast, FL was a potent cofactor for the CD43+B220low progenitor cells, interacting with either IL-7 and/or SCF to stimulate their growth. The combination of FL with IL-7 plus SCF stimulated maximum expansion of these cells, albeit, less than that stimulated in stromal cell cultures. When the CD43+B220low progenitors were divided based on expression of heat stable Ag (CD24) into a CD24- and a CD24+ subset, the FL-responsive cells were contained only within the CD24- subset. FL interacted with SCF or with IL-7 to stimulate their growth resulting in a 20- and 50-fold increase in cellularity, respectively. Since the CD24- subset was the most immature of the B cell populations studied, our data suggest that FL costimulates the expansion of very primitive B cell progenitors.