Cytokine-secreting activity of myeloid and plasmacytoid DC precursors released in peripheral blood after Allo-HSCT. Whole PBMCs obtained from patients at the WBC zenith point were cultured with complete medium and stimulated with either LPS or a specific CpG oligodeoxynucleotide, as described in “Patients, materials, and methods,” and stained for CD33⁺ surface antigen expression and intracellular TNF-α, IL-12 p40/p70 heterodimer, and IFN-α. Percentages refer to myeloid CD33⁺ mononuclear cells and to cultured PBMCs. The experiment shown for IFN-α production following stimulation with CpG oligodeoxynucleotide is representative of at least 3 others similarly performed. The experiment shown for TNF-α and IL-12 following stimulation with LPS is representative of 10 experiments (5 in G-CSF–treated and 5 in untreated patients). In the bottom plots, representative intracellular IL-12 staining, from a patient treated with G-CSF and from another patient not treated, is shown.