Evaluation of TRAIL effects on unilineage committed hematopoietic progenitors at early stages of differentiation (day 4 of culture).

(A) The percentage of cell death was evaluated by annexin V staining in unilineage erythroid (SCF + IL-3 + EPO), megakaryocytic (IL-3 + TPO), and myeloid (SCF + IL-3) cells at day 4. Cultures were supplemented with irrelevant IgM mAb and rHis6-tag peptide (CONT), TRAIL, or anti-CD95 (CH 11) IgM mAb for 20 hours before annexin V staining. Quadrants were set based on negative controls stained with isotype-matched irrelevant mAbs. X-axis: annexin V relative expression. Y-axis: glycophorin A, CD71, CD61, CD33 relative expression. (B) shows CD95 surface expression (thick lane histograms) evaluated at day 4 of unilineage cultures. Isotype-matched negative controls are represented by the thin lane histograms. X-axis: CD95 relative expression. Y-axis: relative cell number.