High expansion of DC from CD34⁺CD40⁺ blood cells. Purified CD34⁺CD40⁺ and CD34⁺CD40⁻ blood cells were grown in liquid culture in the presence of GM-CSF, TNF-, SCF, and FLT-3L for 14 days (see Materials and Methods). The total expansion of each cell fraction at 7, 11, and 14 days is shown in the left quadrant (A), while the absolute number of CD1a+ cells derived from each cell subset at 11 and 14 days of culture is shown in the right quadrant (B). Results are represented as the mean ± SEM values of 3 separate experiments. After 11 or 14 days of culture, there is a 2-log difference in absolute number of CD1a⁺ cells among CD34⁺CD40⁺ versus CD34⁺CD40⁻ blood cells (P = .07).