Irreversible caspase 3 inhibitor fmk-DEVD abrogates the decrease of CFU-C in response to Fas cross-linking in the presence of IFN-γ with or without TNF-α.

Spleen cells were incubated for 24 hours in culture medium alone or in anti-Fas mAb (5 μg/mL) with or without IFN-γ (100 U/mL), TNF-α (10 ng/mL), or both. FMK-DEVD was added 2 hours before the onset of culture at a concentration of 50 μM. IFN-γ, TNF-α, or TNF-α plus anti-Fas mAb had no significant effect compared with culture medium alone (data not shown).