BMMCs were thawed, washed, and barcoded according to manufacturer recommendations (Fluidigm). Barcoded cells were stained using a custom 39-marker panel designed to characterize innate and adaptative immune cell subtypes (online supplemental figure 1). Stained cells were acquired on a CyTOF Helios mass cytometer (Fluidigm). Automated cell classification was performed using the Astrolabe Mass Cytometry Platform (Astrolabe Diagnostics, Inc.). Briefly, immune subsets were clustered into self-organizing maps using the FlowSOM package and labeled using the Ek’Balam algorithm.15 (link) Cell subset definitions follow previously reported definitions of the healthy human immune system and the Human ImmunoPhenotyping Consortium.16 (link) Cell types were excluded if there were less than three cells in at least half of all samples. Plasmablasts, which primarily represent tumor cells, were excluded from the calculation of immune cell frequency.17 18 (link)