Cellular and molecular features that stabilize rolling on selectins under flow

We analyzed rolling of neutrophils or transfected CHO cells expressing PSGL-1 on immobilized P-selectin in a flow chamber. After tethering, cells initially rolled rapidly and unstably but then progressively rolled more slowly and more regularly. Small, uniform rolling steps occurred in cells that developed multiple long adhesive tethers, as visualized by both scanning electron microscopy and differential interference contrast microscopy. Deletion of the cytoplasmic domain of PSGL-1 impaired cytoskeletal interactions and rolling stability but did not prevent extrusions of membrane tethers.