Figure 3.

Gemtuzumab/ozogamicin (GO) impairs CML colony formation. (A) Mononuclear cells (MNC) from 4 CML donors were preincubated in control medium or in GO (5 μg/mL) for 2 h. Thereafter, cells were cultured in methylcellulose in the presence of cytokines for 14 days. The numbers of CFU-GM, BFU-E, and CFU-GEMM were counted under an inverted microscope. Results show the numbers of CFU-GM, BFU-E, and all colonies (total CFU: CFU-GM+BFU-E+CFU-GEMM). Data are expressed as mean±S.D. from 4 donors. *P<0.05 compared to control. (B) Dose-dependent effect of GO (2-hour pre-incubation prior to seeding) on colony-formation of CML cells in one donor. Results show the numbers of total CFU and are expressed as mean±S.D. from triplicates. (C) Numbers of CFU-GM in a long term co-culture-initiating cell assay (LTCIC). MNC of 3 donors were pre-incubated in control medium or GO (5 μg/mL) for 2 h, washed, and transferred to a feeder layer of M2-10B4 cells for three weeks. Thereafter, CFU growth was determined. Data are expressed as mean±S.D. from 3 donors. *P<0.05 compared to control. (D) Numbers of CFU-GM in a LTCIC assay. Cells were maintained in the LTCIC assay in the presence or absence (0) of GO (10 or 100 ng/mL) for three weeks. Then, CFU growth was determined. Results show the numbers (N.) of CFU-GM in 2 donors and are expressed as mean±S.D. from triplicates.