FL plus TGF-β1 cooperate in stimulating DC generation. (A) Effects of TGF-β1 on cell proliferation and differentiation. Ten thousand CD34⁺ CB cells were cultured for 10 days in serum-free medium supplemented with the cytokines FL plus GM-CSF, TNFα, and SCF, with or without TGF-β1, and combined analyzed for the expression of CD1a versus either LZ, MPO, or CD14, respectively, as described in the Materials and Methods. Bars represent mean the percentages ± SEM (left-hand side diagrams) and total numbers ± SEM (right-hand side diagrams), respectively, of cells with the indicated phenotypes observed in five experiments. The number of phenotypically defined cells was calculated from the percentage of cells showing the respective phenotype multiplied by the total number of cells in each culture. (B) Effects of FL costimulation in the absence of TGF-β1. Ten thousand CD34⁺ CB cells were cultured for 10 days in serum-free medium supplemented with the cytokines GM-CSF plus TNFα and SCF, with or without FL, and analyzed by flow cytometry as described above. Bars represent mean percentages ± SEM (left-hand side diagrams) and total numbers ± SEM (right-hand side diagrams), respectively, of cells with the indicated phenotypes observed in three experiments. The number of phenotypically defined cells was calculated from the percentage of cells showing the respective phenotype multiplied by the total number of cells in each culture.