Erythrocyte pausing on neutrophils and dependence on neutrophil activation state.

(A) One of many short-lived pausing events observed as washed erythrocytes were perfused over fibrinogen-adherent, fMLP-activated neutrophils at a wall shear rate of 50 s⁻¹. Following capture, membrane tethering, and a pause for 800 milliseconds, the red cell was released by the neutrophil. Visualization of firmly adhered erythrocytes on untreated neutrophils (B) or fMLP-stimulated neutrophils (C) demonstrated the dependence of RBC adhesion on neutrophil activation after 5 minutes at γ_w = 50 s⁻¹. Identical results were obtained in 3 separate experiments, each conducted with an individual donor. Flow was from right to left.