Phagocytosis Dynamics Depends on Target Shape

A complete understanding of phagocytosis requires insight into both its biochemical and physical aspects. One of the ways to explore the physical mechanism of phagocytosis is to probe whether and how the target properties (e.g., size, shape, surface states, stiffness, etc.) affect their uptake. Here we report an imaging-based method to explore phagocytosis kinetics, which is compatible with real-time imaging and can be used to validate existing reports using fixed and stained cells. We measure single-event engulfment time from a large number of phagocytosis events to compare how size and shape of targets determine their engulfment. The data shows an increase in the average engulfment time for increased target size, for spherical particles. The uptake time data on nonspherical particles confirms that target shape plays a more dominant role than target size for phagocytosis: Ellipsoids with an eccentricity of 0.954 and much smaller surface areas than spheres were taken up five times more slowly than spherical targets.