CD5 and B-cell chronic lymphocytic leukemia: More interesting from a future therapeutic perspective, 200-μM PKHB1 treatment for 2 h killed the CD5+ tumor B cells (~50% of Annexin-V-positive/PI-positive cells) while sparing the residual CD5− B lymphocytes and T cells of the CLL patients (~5% and ~10% cytotoxicity, respectively; Fig. 1G).