Effect of FL on the number of primitive precursors after cultivation of HLA-DR⁺ cells and HLA-DR^dim cells. Mobilized peripheral blood cells were sorted into HLA-DR⁺ and HLA-DR^dim fractions and cultured in [IL-3 + IL-6 + KL] ± FL. After 6 days, cultures were analyzed for the indicated phenotypes. The figure shows the absolute yield of CD34⁺ cells and subsets. FL supported a greater yield of CD34⁺ cells, CD34⁺ CD33^dim cells, and CD34⁺ HLA-DR^dim cells in HLA-DR⁺ cultures than in the HLA-DR^dim cultures. Data are representative of 3 independent trials.