Eosinophils bound to IL-4–stimulated HUVECs. Eosinophils were perfused over (A) control or (B) IL-4–stimulated HUVECs as described in Fig 1. After attachment under shear conditions, video images were obtained using a ×40 objective. These images were captured as described in Materials and Methods and photographs were made. Eosinophils bound to control HUVECs (A) remain phase-bright, whereas eosinophils bound to IL-4–stimulated HUVECs (B) change shape and spread on the monolayer.