Reduced numbers of B-lymphoid progenitors in the BM of flt3L−/− mice.

BM was isolated from the femurs of flt3L+/+ and flt3L−/− mice and cultured in methylcellulose supplemented with rhu IL-7 alone or combined with rmu KL or rhu flt3L to determine the frequency of CFU-B progenitors. Data are presented as the absolute number of progenitors per 2 femurs (n = 8 mice). Data were pooled from 2 experiments and are presented as the mean ± SD. *P < .0001.