Atiprimod induces apoptosis of normal lymphocytes from healthy volunteers. (A) Representative histograms of cells from one healthy donor showing a dose- and time-dependent induction of apoptosis in resting (−PHA) and PHA (+PHA, 3 μg/mL)–activated, gated CD3⁺ T cells. (B) Pooled data from 3 healthy donors showing a dose-dependent induction of apoptosis in gated CD3⁺ T cells and CD19⁺ B cells in comparison with MCL lines. PBMCs were treated with different concentrations of atiprimod for 24 hours, or treated with 2 μM atiprimod for various times. CD3-PE– or CD19-PE–positive stained cells were gated and annexin V–FITC staining was performed in these gated T cells and B cells, respectively, to determine atiprimod-induced apoptosis in normal lymphocytes. Cell apoptosis was confirmed by TUNEL assay (not shown). Results of 4 independent experiments are shown (mean ± SE).