Inhibition of the in vitro formation of irreversibly sickled cells by cepharanthine

S ummary. A method was developed to prepare irreversibly sickled cells (ISC) in vitro under a physiological condition. By exposing sickle red cells to repeated deoxygenation-reoxygenation cycles for 15 h at 37°C, 20–30% of the red cells formed ISC. These cells were separated from biconcave-shaped cells by a gradient density centrifugation. The percentage of the formation of ISC was determined spectrophoto-metrically after cells were haemolysed. Cepharanthine, a bisbenzylisoquinoline alkaloid, was found to inhibit this in vitro formation of irreversibly sickled cells by 50% at 15 μM. This concentration was much lower than that required to inhibit the in vitro sickling.