CD34⁺CD33^lo thymocytes develop efficiently into DCs in multicytokine-supported cultures. CD34⁺CD33^lo thymocytes were cultured for 10 days with the cytokine mixture described in Fig 2. Biparametric histograms on the left show the correlated expression of CD44 and CD33, CD44 and CD4, CD44 and CD1, CD40 and CD33, and CD7 and CD13 on the cultured cells. Background fluorescence values were set by use of FITC- and PE-conjugated isotype-matched irrelevant antibodies. Monoparametric histograms on the right show the expression of HLA-DR, -DP, and -DQ, CD11c, CD80, and CD86 (shaded histograms) on the same cultured cells. Background fluorescence (unshaded histograms) was determined by staining with isotype-matched irrelevant MoAbs plus PE-conjugated goat antimouse Igs.