GM-CSF withdrawal induces apoptosis in DCs.

DCs were cultured as described in “Materials and methods.” At day 6, DCs were harvested, extensively washed, and further cultured in RPMI-10% FCS supplemented with IL-4 (10 ng/mL) plus GM-CSF (5 ng/mL; designated as “GM-CSF” in panels B and C), IL-4 alone (10 ng/mL; designated as “No GM-CSF”), or GM-CSF alone (5 ng/mL; designated as “No IL-4”). After 48 hours of incubation, cells were analyzed for the amount of apoptosis using Hoechst to analyze nuclear morphology (A), PI to detect DNA fragmentation (B), or Rh123 to investigate ΔΨ_m (C). Photographs (original magnification, × 400) taken from cells stained with Hoechst were inverted and demonstrate condensed (“C”) and fragmented nuclei (“F”) indicated by arrows (A). Data presented are representative of 5 independent experiments with different donors.