CD34⁺ cells from a FA-C patient exposed to 0.1 ng/mL IFN-γ demonstrate a hypersensitivity to this mitotic inhibitor when compared to CD34⁺ cells from a healthy donor.

FA-C CFU-GM (A) (P = .036 by 2-way ANOVA) and BFU-E (B) (P = .0185) clonal growth was enhanced by the addition of ac-DEVD-cho (50 μmol/L), but not by ac-YVAD-cho, indicating involvement of caspase 3 but not caspase 1 in the IFN-γ–induced apoptotic pathway in these cells. Colony growth of normal CD34⁺ marrow cells was not affected by the caspase inhibitors. Colony growth was expressed as “% control,” where control cells were cultured in the absence of IFN-γ. Graphic data represent 2 separate experiments.