TNF- induction of CD40 on myeloid CD34⁺blood cells. Three-color staining with CD34PerCP, CD40FITC, and PE-conjugated MoAbs specific for myeloid (CD13, CD33), monocytic (CD14), dendritic (CD1a), and lymphoid (CD19, CD3) lineages was performed on freshly isolated CD34⁺ blood cells and after 24 hours of culture with medium alone or TNF- (10 ng/mL). Cells that fluoresced brightly for anti-CD34 MoAb were gated for analysis.