Hydrodynamic Collisions Suppress Fluctuations in the Rolling Velocity of Adhesive Blood Cells

The slow rolling motion of white blood cells transiently adhering to the interior surface of venules under shear is simulated numerically. Molecular bond breakage events cause a noisiness in rolling velocity over time scales longer than the lifetime of an individual bond. It is shown that the hydrodynamic interactions between particles produce a smoother rolling behavior, by modulating the cell's motion during the brief forward jumps following a bond breakage event. Good agreement is found with flow chamber experiments using adhesive spherical beads.