FIG. 2.

Proliferation stimulation and desensitization of human leukemic cells to the chemotherapeutic agents by IL-27. (A) Human leukemic cell lines were deprived of GM-CSF or EPO and cultured in 5% or 10% serum assay medium containing IL-27 at increasing concentrations. Dose–response relationships of IL-27 stimulation to cell proliferation were measured by ³H-thymidine incorporation after 2- or 3-day incubation. (B) Human leukemic cell lines were deprived of GM-CSF or EPO and cultured in 2% serum assay medium containing IL-27 at increasing concentrations. Dose–response relationships of IL-27 treatment to cell viability were measured by formazan production after 48 h of incubation. (C) TF-1 cells were deprived of GM-CSF and cultured in 5% serum assay medium containing IL-5 in the absence or presence of either TGF-β3 or IL-27 at indicated concentrations. Cell proliferation was measured by ³H-thymidine incorporation after 2-day incubation. **P < 0.01 for IL-5 plus TGF-β3 versus IL-5 alone. *P < 0.05 and **P < 0.01 for IL-5 plus IL-27 versus IL-5 alone. (D) OCI-AML5, TF-1, UT-7, and UT-7/EPO cells were deprived of GM-CSF or EPO and cultured in 5% or 10% serum assay medium containing cytarabine or daunorubicin at the indicated concentrations in the absence or presence of 200 ng/mL IL-27. Cell proliferation was measured by ³H-thymidine incorporation after 2-day incubation.