Dynamic switching of macrophage phagocytic polarity between opposing targets

How macrophages reprioritize competing phagocytic targets under persistent spatial competition remains unclear. Here, using a dual-microneedle assay in which opposite sides of a single macrophage were sequentially stimulated, we examined how phagocytic polarity established toward one target is redistributed when an opposing target continues to compete. Membrane extension did not converge on stable dual extension after contact with the second opsonized microneedle. Instead, dominance switched reciprocally between the two phagocytic fronts, and the same pattern was reproducibly observed in five additional cells. Local cross-correlation analysis showed that anti-phase coupling between the two fronts was enriched within switching windows, whereas non-switching intervals showed weaker or qualitatively different coupling. These switching windows were also associated with opposite directional biases in cell velocity, consistent with coupling between local front switching and whole-cell movement polarity. These findings support a multiphase switching process in which macrophage phagocytic polarity remains dynamically reconfigurable under persistent competition between opposing targets.