Flow cytometric evaluation of CD34⁺ cell apoptosis in MDS.

Bone marrow mononuclear cells from patients with MDS RA (A), RAEB (B), and RAEB-t (C) were isolated by density gradient centrifugation and incubated with phycoerythrin (PE)-conjugated anti-CD34 monoclonal antibody (Mab) and fluorescein isothiocyanate (FITC)-conjugated annexin V. Analysis was based on gating on CD34⁺ cell subpopulations (S) by forward scatter versus side scatter as well as side scatter versus fluorescence 2 (FL2) (i). Percentage of positivity was determined by comparison of the fluorescence distribution histogram (FL1) of positively stained cells (iii) to that of cells to which no annexin V was added (ii).