Fas expression and cytotoxic effect of FasL against Ph1-positive leukemia cell lines.
(A) Dose response of growth inhibition. CML-BC–derived (left panel) or Ph1-positive AL-derived (right panel) cell lines were cultured for 42 hours in the absence or presence of indicated concentrations of rhsFasL, and 3H-thymidine uptake was evaluated for the last 6 hours. FasL-sensitive T-cell leukemia cell lines (Jurkat and MOLT4F) were also included as positive controls and are shown by the dotted lines. Data with myeloid cell lines are shown as the closed symbols. All data are represented as the mean of triplicate samples. Standard errors were always less than 10% (not shown). (B) Time course of cell viability. CML-BC–derived (left panel) or Ph1-positive AL-derived (right panel) cell lines were cultured with or without 100 ng/mL rhsFasL for 12, 24, or 36 hours, and then the viability was determined by the trypan blue exclusion assay. Data with Jurkat and MOLT4F are also shown by dotted lines. Data with myeloid cell lines are shown as closed symbols. All data are represented as the mean of triplicate samples. Standard errors were always less than 10% (not shown). (C) Cell-surface staining of Ph1-positive cell lines with anti-Fas mAb. CML-BC–derived FasL-sensitive (Nalm1) or -resistant (KOPM53) cell lines and Ph1-positive AL-derived FasL-sensitive (KOPM30) or -resistant (KOPN30bi) cell lines were stained with control mouse IgG or antihuman Fas mAb and analyzed by flow cytometry. Shaded and unshaded peaks correspond to specific and control stainings, respectively. RFI is indicated in each panel.
