Exposure of CD34⁺cells to imatinib mesylate inhibits their differentiation into DCs in a concentration-dependent manner. (A) Mobilized human CD34⁺ PBPCs were cultured in the presence of GM-CSF and TNF-α for 10 to 16 days with or without imatinib mesylate. (B) CD34⁺ PBPCs were cultured in the presence of GM-CSF, TNF-α, IL-4, and FLT3L with or without imatinib mesylate. Cells were analyzed by flow cytometry for expression of the DC markers CD1a and CD83 and costimulatory molecules CD80, CD86, and CD40. The level of surface expression is indicated as mean fluorescence intensity. (C) Mobilized human CD34⁺ progenitors were cultured in the presence of GM-CSF, TNF-α, IL-4, and FLT3L with or without imatinib mesylate in different concentrations (1-5 μM). Fluorescence-activated cell sorting (FACS) analyses were performed to determine the phenotype of the generated cell populations. The level of cell surface expression is presented as mean fluorescence intensity.