Differentiation of human CD34⁺ cells into BDCA-2⁺ cells. UCB CD34⁺ cells were cultured on either OP9-Del1 or OP9-C stroma for up to 3 weeks in the presence of FL and IL-7 cytokines. (A) Flow cytometric analysis of the expression of BDCA-2 and CD14 on the cultured cells at 1, 2, and 3 weeks (W) of culture. These plots represent 1 representative kinetic experiment of 2. Numbers indicate the percentage of cells in each quadrant. Irrelevant Ig controls provided less than 2% background staining. (B) Percentages and numbers of BDCA-2⁺ and CD14⁺ cells produced after 10 and 20 days of culture. The data are from 13 different experiments, each represented by a symbol. Average values are indicated by a bar with representation of standard deviation values. Statistical analysis compared the control and Del1 groups at each time point, and the P values of the paired t test are indicated.