Centrifugation attenuates the fluid shear response of circulating leukocytes

Human leukocytes retract pseudopods in response to physiological fluid shear, a phenom- enon that serves to keep circulating leukocytes in a spherical state. We show here that leukocyte fluid shear response is attenuated irreversibly by cen- trifugation. Inhibition of shear response depends on duration and magnitude of acceleration during centrifugation and time duration after centrifuga- tion. Even after low-speed centrifugation, leuko- cytes no longer retract pseudopods during shear application. After centrifugation at higher acceler- ation, leukocytes project pseudopods instead of retracting during shear application, which can be suppressed by a calcium channel blocker. We ex- amined the role of fluid shear response in vivo by reintroduction of centrifuged cells into the rat cir- culation. Centrifuged leukocytes have a signifi- cantly enhanced tendency to migrate into tissue. These observations indicate that centrifugation may irreversibly damage the fluid shear response of leukocytes. It causes an impaired leukocyte be- havior after reintroduction into the circulation, suggesting that shear response is a requirement for normal passage of leukocytes through the micro- circulation. J. Leukoc. Biol. 72: 133-139; 2002.