Figure 2. All trans retinoic acid accelerates B lineage potential in culture.

One hundred highly purified ELP were co-cultured with OP9 stromal cells in 96 well flat bottom plates for four or seven days with ATRA or 0.1% ethanol diluents, and then the four day cultured cells were transferred to Pre-B colony medium (A) and the seven day cultured cells were subject to flow cytometry to examine the production of CD19⁺B220⁺ cells (B). Total Pre-B colony numbers were scored after 7 days of culture. Sorted ELP were treated with different concentrations of ATRA ranging from 10⁻⁸ to 10⁻⁶ M for 7 days and subject to flow cytometry, total cell yields (C) and B lineage lymphoid cell yields (D) were calculated. All treated groups were then compared with the control group using student t test. Data are reported as mean ± S.D for n= 4-6. *, p < 0.05, and **, p < 0.01. The results shown are representative of five independent experiments.