Morphologic analysis of monocytes and day-3 monocyte cultures with GM-CSF plus IL-4 or M-CSF. Cytospin slides from uncultured purified monocytes were stained with Giemsa (lens magnification, × 100; scale bar is 10 μm). Cytospin slides from day-3 cultures of monocytes with GM-CSF plus IL-4 or M-CSF in the absence or presence of LPS were analyzed unstained by phase-contrast microscopy or processed for the detection of NSE and counterstained with toluidine blue (final magnification, × 100; scale bar is 25 μm). Single and double arrows indicate strongly and weakly NSE-positive cells, respectively, corresponding to immature and mature DCs.