Cell culture and establishment of imatinib-resistant cell line

The following cell lines, KCL22 (parental and IR), K562, HH, and human peripheral blood mononuclear cells (PBMCs) were maintained using complete RPMI-1640 media (HyClone) containing 10 % fetal bovine serum (FBS, Atlanta Biologicals), 2 mM L-glutamine (Corning), 50 mg/ml penicillin-streptomycin (Corning). Kit225 and Baf3 cell lines were maintained in complete RPMI-1640 media supplemented with 100 IU/ml IL-2 or 100 IU/ml IL-3, respectively. HEK293 and HepG2 cells were maintained in DMEM high glucose (HyClone,) containing 10 % FBS, 2 mM L-glutamine and 50 mg/ml penicillin-streptomycin. The imatinib-resistant cell line was developed by maintaining parental KCL22 cells in culture with imatinib concentrations of 500 nM, 750 nM, or 1 μM during weeks 1–2, weeks 3–4, and weeks 4–6, respectively. During this 6-week period, KCL22 cells were passaged at 40 % of the standing population and imatinib concentrations replenished every 3 days. Cell population number was consistently maintained between 5 and 10 million cells per milliliter.