G-CSF blocks Fas-induced caspase activation in MDS bone marrow cells.

(A) MNCs from patients with RA and patients with RARS were incubated for 8 hours in the presence or absence of G-CSF (100 ng/mL) and subsequently assessed for caspase-3–like activity. This caspase activation was diminished by G-CSF in RARS (P = .0005), while no significant effect was observed in RA (P = .21). G-CSF did not influence caspase-3–like activity in NBM cultures (data not shown). (B) Cells incubated as above were also assessed for caspase-9 activity. A significant inhibitory effect of G-CSF was seen in patients with RARS (P = .005), but not in patients with RA.