Cell-cell interactions occur over a wider range of shear stresses with increased concentrations of PMPs.

HL-60 cells incubated with various concentrations of PMPs generated by calcium ionophore were withdrawn over HL-60 cells prebound to an antihuman CD43 mAb-coated glass slide. The number of transient cell-cell interactions was counted and normalized for the number of cells on the surface, duration of the experiment, and flux of cells passing through the flow chamber. *Indicates that there were significantly more cell-cell interactions with 0.8 mL PMPs than with 0.1 mL PMPs (P < .05). The data are representative of 4 independent experiments.