Neutrophil infiltration and endothelial integrity during the early phase of the cutaneous rpA reaction. The integrity of the endothelial cell layer at sites of neutrophil infiltration during the cutaneous rpA reaction was investigated by intravital microscopy. Endothelial cells, platelets, and neutrophils were stained using fluorescent antibodies to CD31, GPIbβ, and Ly-6G, respectively. In all groups of mice, although faint CD31 staining (arrowheads) was found in areas of neutrophil infiltration, the endothelial cell layer was overall well preserved. All pictures were taken during the first 3 hours of reaction. Scale bar, 100 µm.