Leukemia Cell Apoptosis Quantification

Leukemia cell apoptosis was determined based on measurement of the binding of Annexin-V-FITC (BioLegend, San Diego, CA) or Pacific Blue Annexin-V (BioLegend), whereas loss of cell viability was measured by 7-AAD labeling (BioLegend), according to the manufacturer’s procedures. For receptor-binding experiments, cells were incubated under saturating conditions for 1.5 hours on ice in PBS with anti-CD79b-APC antibody (BioLegend) or anti-VpreB-PE antibody (BioLegend). Flow cytometry data were calibrated with QuantumTM Simply Cellular beads (Bangs Laboratories, Fishers, IN) with anti-mouse Fc antibody according to the manufacturer’s instructions. Dissociation constants were estimated with nonlinear regression analysis under K_D-controlled conditions as described previously (92 (link)). All flow cytometry data collection was conducted on HyperCyt (93 (link)) or BD LSRFortessa flow cytometers and analyzed with the FlowJo Software Suite (Tree Star, Ashland, OR).