Phenotypic characterization of untreated and TRAIL-treated HL60 cells by immunofluorescence staining revealed by flow cytometry.

(A) Representative analysis of surface CD33, CD15, CD14, and CD11b performed at 24 hours of TRAIL treatment (0.2 μg/mL). Analyses were performed by gating viable cells. Control (unshadowed) histograms represent the background fluorescence obtained from the staining of the same cultures with isotype-matched control mAbs. In some panels, the unshadowed histograms are not visible because they are completely overlapped by the shadowed histograms. The shift of the shadowed histogram along the x-axis illustrates the induction of CD14 and the increased level of CD11b in a subpopulation of the TRAIL-treated culture. Data shown are from a single experiment representative of 8 independent experiments with similar results. (B) Dose-dependent effect of TRAIL on surface CD14 expression, evaluated by flow cytometry and reported as a percentage of CD14⁺ cells. Data represent the means ± SD of 5 independent experiments performed in duplicate.