Reticulated platelets are resistant to ABT-263-induced apoptosis. Washed platelets of healthy volunteers or CLL patients were incubated in annexin buffer plus 50 ng/mL thiazole-orange and different concentrations of ABT-263 for 2 hours. Apoptosis was assessed in the thiazole-orange-positive (reticulated) or -negative (nonreticulated) platelet population by staining with annexin V/allophycocyanin and gating by flow cytometry. Data are mean ± SD (n = 4). *P < .05.