THROMBOPOIETIN STIMULATES PROLIFERATION AND MEGAKARYOCYTIC DIFFERENTIATION OF MOUSE PRO-B CELL-LINE BF-TE22

We have isolated and characterized a thrombopoietin (TPO)-dependent BF -TE22 cell line endogenously expressing murine Mpl, which is a subclon e of murine pro-B Ba/F3 cells. TPO stimulated the proliferation of BF- TE22 cells in a dose-dependent manner, and also induced the expression of megakaryocyte lineage-specific AP-51 and CD61 cell surface antigen s. The results indicate that the murine Mpl on BF-TE22 cells can trans mit both proliferation and megakaryocyte lineage-specific differentiat ion signals to cells. Furthermore, it was shown that IL-3 inhibits the TPO-induced differentiation signals of BF-TE22 cells. These results s uggest that the signals mediated by IL 3 predominate over those of TPO in BF-TE22 cells. Thus, BF-TE22 cells will be useful for the biologic al and biochemical studies of the TPO-Mpl signal transduction mechanis m.