Factors which influence blood platelet migration.

Migration of human blood platelets in vitro was investigated by a modification of the capillary-tube migration chamber technique used to study the migration inhibition factor of macrophages. Platelets were packed in capillary tubes and incubated in autologous platelet-free plasma (PFP). The extent of migration was quantified by planimetry (measurement of the area of platelet migration visible by stereomicroscopy). Among the various anticoagulants employed, sodium citrate was most suitable for studying platelet migration. Optimal migration occured at 22 degrees to 37 degrees C and pH 7.2 to 7.4. Migration was inhibited by metabolic inhibitors such as iodoacetic acid, sodium fluoride, and 2,4-dinitrophenol, and inhibition was proportional to the dose of the agent added to the incubation medium. Mobility was also inhibited by cytochalasin B, which disrupts cellular microfilaments, at 1 microgram/ml PFP, but not by colchicine, a microtubule inhibitor, even at 40 microgram/ml of PFP. Light and electron microscopy showed that this inhibition was not ascribable to platelet clumping. These observations suggest that platelet mobility is an active process. The possible significance of platelet migration in hemostasis is discussed.