Cell-surface expression of TRAIL receptors on Ph1-positive leukemia cell lines.

(A) Specificity of mAbs against human TRAIL receptors. The parental BHK and the transfectants stably expressing human DR4, DR5, DcR1, or DcR2 were stained with control mouse IgG or murine antihuman DR4, DR5, DcR1, or DcR2 mAbs and analyzed by flow cytometry. Dotted and solid lines correspond to control and specific stainings, respectively. (B) Cell-surface staining of Ph1-positive cell lines with anti-TRAIL receptor mAbs. CML-BC–derived TRAIL-sensitive (KOPM28) or -resistant (KOPM53) cell lines and Ph1-positive AL-derived TRAIL-sensitive cell lines (KOPM30 and KOPN72bi) were stained with control mouse IgG or antihuman DR4, DR5, DcR1, and DcR2 mAbs, and analyzed by flow cytometry. Shaded and unshaded peaks correspond to specific and control stainings, respectively. RFI is indicated in each panel. (C) Correlation between the cell-surface DR4/DR5 expression and the growth inhibition by TRAIL. The horizontal axes represent the RFI of DR4 and DR5. The vertical axes represent the percent inhibition by TRAIL (100 ng/mL).